Wayne Levi shot a four-under-par 68 to take a four-shot lead over Bobby Cole after 54 holes of the $350,000 LaJet Classic in Abilene, Tex. Cole, who began yesterday's round tied with Gary Koch at 138, birdied the 14th and 19th holes on his way to a 69.

PGA champion Ray Floyd, who mistakenly believed he'd missed the cut after his round Friday and immediately flew home to Miami, was unable to make airline connections to return to the LaJet tourney yesterday and so virtually clinched the year's money-winning title for Craig Stadler.

Floyd, No. 2 on the year's money-winning list, commented, "Well, I did it again, didn't I?" It was the second time this year Floyd had left a tournament, thinking he'd missed the cut, only to discover he had, indeed, qualified and was eligible to play the final two rounds. The first time it happened was at the Tournament Players Championship in Ponte Vedra, Fla., March 19. He was able to get back to that tournament in time . . .

Alton Duhon of Los Angeles, a retired postal worker, defeated defending champion Ed Updegraff of Tucson, Ariz., 2 up, to win the 28th U.S. Senior Amateur championship in Tucson. Duhon, a public course player, became the first black to win the event.