1996 Dodge Avenger shuts off while driving

I have a 1996 Dodge Avenger that shuts off while im driving. It has been doing this for awhile. I took it to a shop and they said it was the computer so I bought a used one and had it replaced. I still have the same problem. I dont know if it is because I bought a used computer or the computer is not the problem. But the check engine light is always on. When it shuts off while im driving the the check engine light will go off. I would have to get out and tap then computer with a wrench or somthing and then the check engine light would come back on and then the car would start. But now the car will not start at all. Does any one have a clue about what might be wrong with it?