Craig Stadler's face was a furnace only a shade lighter than his crimson mustache. His mouth worked furiously with annoyance as he shouldered his way through hundreds of grazing golf fans. His moment of glory was being ruined.

Instead of striding down the panoramic 18th fairway of Congressional Country Club in a proud and leisurely walrus waltz that would befit his six-shot runaway win in the Kemper Open, Stadler was searching for a lousy lost ball.

What a time to be looking under Volvos and Mercedes-Benzes, peeking behind stinking garbage compactors, and gazing occasionally into the limbs of pine trees on the off chance that the miserable ball might be lurking there.

"Anybody lose a Titleist 4?" asked one smart aleck, drawing a glare from Stadler.

Stadler was ready to spit nails. Somebody had stolen his ball and he darn well knew it. Thirty-thousand forecaddies and he was going to have to take a two-shot penalty and head back to the tee to drive again.

Then, the good Samaritan spoke.

"A kid stole it," said Dr. Steve Sheehy of Falls Church. "Picked it up and stuck it in his pocket."

Quickly, official Glen Tait was on his walkie-talkie to Tour Director Jack Tuthill, asking, "Is that reasonable evidence that it was Craig's ball or does he have to go back and hit again?"

"Odds are there wouldn't be another ball sitting out here under the trees this time of day," growled Stadler.

"Okay, Craig, drop another one here and it's in play. No lost ball and no penalty," said Tait.

In the clubhouse, Tom Watson, who shot a face-saving but never-in-contention 67 to end up in a distant tie with Tom Weiskopf for second place at 276 ($35,200 each), laughed. "He could lose three balls and still win," said Watson, knowing that all Stadler needed for victory on that last par-4 hole was a sextuple-bogey 10.

So, Stadler chipped safely through the undergrowth back to the short grass, then savored his victory strut as he completed a routine bogey. Sucking in his newly svelte gut, twitching his merry mouth under his huge lip growth, Stadler soaked up the adulation of the 31,500 fans. After all, how often does a man shoot 10 under par (67-69-66-68--270) to break the course record at storied Congressional by five whopping strokes? How often does a guy step to the 72nd hole of an event with a $72,000 first prize and know he has a seven-shot lead, plus a streak of 28 consecutive bogeyless holes?

However, Stadler can't do anything the easy way. Even this afternoon's splendidly lopsided route was not the bluebird stroll in the countryside that it seemed to the millions of TV viewers who watched Stadler enter their video view with a comfortable four-shot lead and just five holes to play.

The golf masses may have thought that Stadler endured no pressure this day, survived no torments, as he entered the round with a two-shot lead, never saw it dwindle as he parred the first 12 consecutive holes, then lapped the field with a birdie-birdie-par-birdie sprint that began at the 13th hole.

Even Stadler contributed to the misimpression, saying, "The wind made it hard to make birdies today, but not too tough to make pars. And all I had to make was pars. Nobody made a run at me all day, when I made a couple of birdies (at 13 and 14) and breezed on in."

Perhaps the only two people at Congressional who knew better were Stadler and his wife Sue. And she blew the whistle.

"I was very scared early. The way Craig plays the first hole, or the first few holes, especially in the last round, is almost always the way he plays the whole day. He's so streaky . . . either way," she said. "For the first five holes, he had to get it up and down (for par) from everywhere. He could very easily have shot 74."

Or more.

For the first three days here, Stadler probably played the best tee-to-green golf of his life. For the first 12 holes yesterday afternoon, he hit the ball every which way but straight, yet parred every hole; thanks to five superb greenside saves from jail and one tremendous 200-yard seven-iron shot from tough rough. The wheels of his emotional stick of dynamite were wobbling wildly, yet he kept them on, gradually rediscovered his iron game, hit a short four-hole hot streak, then, as he said, "limped home."

The two gentlemen playing with Stadler -- Weiskopf (72) and John Cook (73--277 for fourth place and $19,200) -- were the only players with any honest chance of catching Stadler and they did everything possible to prevent it.

Weiskopf gave a perfect reprise of the last half-dozen years of his disappointing career. While Stadler was everywhere, Weiskopf was down the watering system every hole. While Stadler was saving par from a greenside gulch at No. 1, saving par from a trap at No. 2, saving par from a forest of pines at No. 4, saving par from the fringe at No. 5, saving par from the deep rough at No. 10, saving par from more rough at No. 11, Weiskopf was calmly surveying six birdie putts of less than 15 feet (plus three others only slightly longer), then missing every one by a healthy margin.

Weiskopf's familiar frustration grew as he sought out more and more airplanes and fans to glare at, until finally, as soon as the TV cameras hit him at the 14th, he drove into trees and took double bogey. As soon as he was out of it, as soon as his chances for this desperately desired win were completely gone, he immediately sank a 50-foot birdie putt at the 16th.

Cook was hardly a more pleasant story. He started out like a 23-year-old nervous wreck, three-putting the first two greens with routine lag putts that came up 10 and 15 feet short, causing even novice spectators to hide their eyes. Then, however, Cook showed his guts with birdies at the third, sixth and ninth holes. It should be said, however, that both times Cook got back to six under par -- just two shots behind Stadler and back in the running -- he immediately three-putted the next hole (seventh and 10th) to kill himself all over again.

It was Stadler, who always has combined titanic length with pick-pocket touch, who finally showed the signs of mature self-management that might make him a major star. "I took some bad swings the first five holes," said Stadler, who was eighth on the money list last year and now has $146,452 in '81. "I almost whiffed a two-iron at No. 2. After a few holes, I had a little talk with myself. . . I didn't really hit my first solid shot right at the hole until the 13th. But as soon as I made that birdie (from five feet), I knew I had it. The other guys could start playing for second."

Just five weeks ago, Stadler was in such a slump that, he said, "I couldn't shoot 76. In three weeks, I think I made $1,000. I couldn't have felt lower. Now, I shoot 10 under a helluva course. It's all a mental game out here."

"It's a spooky sport, especially for us, because nobody's streakier than Craig," said his wife. "When it's sour, like it was a month ago, you just live through it. And when it's good . . ." she said, looking at the $8,000 vase that is part of a $20,000 Waterford crystal set that also goes to the Kemper winner, "I got a new china closet for Christmas and that goes right in the middle of it."

Sue Stadler was sitting in a breezy open-air gazebo midway between the lake-surrounded 18th green and the Taj Mahal Congressional clubhouse. The Stadlers' 16-month-old son Kevin was playing with a golf ball. Suddenly, Kevin, sitting perhaps three feet from the vase, decided to throw the ball. His fling zipped past the crystal heirloom, and bounced away harmlessly.

"He's Craig's son," said Sue Stradler. "His luck is holding."