DES MOINES, Iowa (AP) _ Newspaper carrier Johnny Gosch, missing for more than eight years, would have been 21 Monday and his mother says the pain of not knowing what happened to him gets worse with time.

Noreen Gosch's son disappeared Sept. 5, 1982, from a street near his home just as he was about to begin delivering Sunday newspapers.

''Most of the time, I'm really good. I distance myself from the pain, I put it on the shelf,'' said Mrs. Gosch, of suburban West Des Moines. ''But every so often, something will sneak in, a memory, a song. Without realizing it, you're reduced to tears in seconds, it hits so fast.

''I've been through a lot of losses, but it is different when you don't have an answer.

''The longer it goes, you'd think it would be further removed emotionally, but it kind of works the opposite.''

''We've missed all the years of him growing up, it's painful. We were at a family gathering recently, and a lot of nieces and nephews were there. There are a lot of them Johnny's age. It's real hard going to someplace like that, you see everybody else's kid grew up,'' she said.

The most devastating news, she said, was when investigators turned up a false alarm last spring - the body of a man bearing identification of John Gosch was found in Mexico. But it turned out the body was that of a man with the same name and age who had disappeared from Tacoma, Wash., three years earlier.

''We came close to an answer, even though it would have been a bad one. That was real tough. It was hard on us emotionally,'' she said.

In the months following Johnny's disappearance, the Gosches raised tens of thousands of dollars to publicize the case and hire private investigators.

Mrs. Gosch also renewed her appeal for a Michigan man, released from prison last year after serving time for defrauding the Gosches, to contact the family about possible clues in the case.

Robert Herman Meier of Bay City, Mich., contacted them several years ago and asked for money in return for information on the abduction. The Gosches, convinced that Meier was credible, gave him $10,000.

Meier later pleaded guilty to fraud and served about 18 months. He as released from an Iowa prison about a year and a half ago. No money was recovered.

She said the state parole board will not give them information on Meier's whereabouts, agreeing only to send him a letter inviting him to contact the family.