It's a terrible affliction these Dallas Cowboys are now fighting. For some reason, they have been losing their interest and their leads late in games, turning from rugged Conans to disappearing Caspers in a blink.

They lost a 14-6 fourth-quarter lead to Philadelphia two weeks ago, botching a chance for a two-game lead in the NFC Eastern Division. Then on Monday night, they allowed the St. Louis Cardinals to excavate themselves from a 10-point halftime deficit for a 21-10 shouldn't-have-happened victory.

Consequently, instead of carrying a one-game division lead to Washington's RFK Stadium where they will play the Redskins Sunday, the Cowboys will carry the weight of uncertainty on their shoulders. They are 6-3, tied with the New York Giants in first place, one game ahead of the Redskins, as the season continues on a remarkable course of divisional ebb and flow.

To a man, the Cowboys wonder, what gives?

"In past years when we got a team down, they stayed down," said running back Tony Dorsett, who had 65 yards on 15 carries Monday night. "I mean we gave them no light, no air, no nothing. Now, we get out there and mess around and let teams come back.

"I think (safety) Dextor Clinkscale said it best. He said, 'We gotta learn how, when we get teams down, to kick 'em, spit on 'em, throw dirt on 'em, whatever.' We have to get that kind of attitude. We don't have it now."

You never figure the Dallas Cowboys to have problems with attitude, not with their 249-victory coach, wearing the stylish fedora and the look of seriousness and purpose on his face.

But even Tom Landry said in the wee hours of this morning, "Intensity comes and goes with football teams over a season. Sometimes you have it, sometimes you don't. Sure, this (second-half letdown against St. Louis) bothers me, but we've played this way other times this year, so it's not unusual. If we're going to do anything this year, we've got to eliminate it."

John Dutton, the veteran defensive tackle, said, "I'm not sure that we know what we're doing sometimes. We have got to be more serious about what we're doing."

It should be pointed out that Landry and his players spoke similar words prior to playing the Redskins late last season and Coach Joe Gibbs accused the Dallas thinkers of concocting a "propaganda ploy."

Yet, if you saw the Eagles' quarterback, Ron Jaworski, slice up the Dallas pass defense for a career-high 380 yards on Oct. 20 while Dorsett and reserve quarterback Gary Hogeboom kept making turnovers or if you saw Neil Lomax spinning second-half passing magic Monday night without injured all-pro receiver Roy Green, while White was getting sacked four times, you realize that this isn't propaganda.

"Maybe we have got to work on an attitude readjustment at halftime," said safety Dennis Thurman, who remembers a time when Dallas used to own the fourth quarter, not sell it.

"Different players," Thurman said. "Different attitude."

One week, the Cowboys intercept five Joe Theismann passes, and one by his relief, in a 44-14 season-opening victory over the Redskins. The next week, they commit five turnovers and lose to Detroit, 26-21.

Then they win four straight games, knocking off Cleveland, Houston, the Giants and Pittsburgh. Dallas intercepts 11 passes during the streak, White has two games with more than 340 yards passing, Dorsett pulls off two more 100-yard games and you become convinced that Doomsday is back.

Sitting on that four-game victory streak, Cowboys President Tex Schramm had said before the Eagles game that the lapses in his team's intensity over the past two seasons seemed to have disappeared. New, young leaders were being molded, he said.

Then Jaworski cut down the Cowboys. Dallas slipped past Atlanta, 24-10, despite committing four turnovers a week later. Then came St. Louis. No propaganda here. Just inconsistency.

"We're making some games close that shouldn't be close," cornerback Everson Walls said. And wide receiver Tony Hill said, "All I know is that we have the No. 1 offense in the league (in total yardage) and we should be scoring more points. Tonight was the story of our lives, the same old thing: we didn't play well in the end when we had to."

The Cardinals' turnaround began with a freaky play, the kind of divine intervention that pumps life into a 3-5 team that has a coach (Jim Hanifan) whose job security reportedly is jeopardized by the dwindling patience of the owner (Bill Bidwill).

Trailing, 10-0, in the third quarter, Lomax threw over the middle for J.T. Smith, who as the emergency fill-in for Green had a fine game (six catches for 86 yards, virtually matching the night's figures for NFC receiving leader Hill). The ball deflected off Smith's hands and was caught by Pat Tilley, for a 46-yard touchdown play that swung the game's momentum.

"I didn't even know (Tilley) had the ball," Walls said. "J.T. and I were running across the field. I thought the play was over."

Rookie cornerback Ricky Easmon was a step behind Tilley. "I was late in getting my hands up," Easmon said, "and he caught it."

"I don't know if our season was at stake," Hanifan said. "But certainly our self-respect was."

"When a team is playing out of desperation, it can get things done," said White, who has thrown 10 touchdown passes and 13 interceptions this season. "(The Cardinals) were desperate coming in and then when they fell behind 10-0, they were more desperate."