my check engine light turns on and off was wondering why? on 1994 Mercury Villager

i took it to autozone to get checked and they said they couldnt because they can only check 96 and up.

Asked by for the 1994 Mercury Villager
seek a diag and est from your mech
1 more answer
look at this youtube. http://www.youtube.com/watch?v=wnKJ4QD0Rq4