Davey Johnson, who led the New York Mets to the World Series title last season, will make 1988 his final year as manager, the club announced.

Johnson, 44, will relinquish the managerial job and become a special assistant to the vice president for baseball operations, Joe McIlvaine, beginning in 1989, General Manager Frank Cashen said. Next year will be Johnson's last under a three-year contract.

"I enjoy managing a great deal and want to stay with the organization," Johnson said. "I'm looking forward to coming back next year. Beyond that, I'm very comfortable {in the new role.}" In 1989, Johnson's chief responsibility will be to evaluate talent . . .

Also, Seattle Mariners Manager Dick Williams says he plans to retire from a 42-year baseball career, including two world championships, after the 1988 season.

"Next year will be the last year of my contract and I've been in the game for 41 years, so I think it's the time," said Williams, 58. "This will give the club enough time to find a successor." . . .

The Boston Red Sox renewed the contract of veteran outfielder-first baseman Dwight Evans for the 1988 season. Evans, who will be 36 on Nov. 3, is winding up his finest season in 15 years with the Red Sox, hitting .306 with 34 homers and 122 RBI.