after thinking about this more, other things that may cause it is the cam sensor or even cheap plugs & plug wires. on my park ave i bought cheaper plugs & wires only to (basicly) burn them up w/in about a year. i switched to AC/DELO platinium plugs & wires & ran them for the next 3yrs w/o problems(then i sold the car when we bought our 05 trailblazer). i really dout it's a computor but IF it is dont waste ur time on a used one, the new (AC/DELCO) ones have been updated several times.
the guy who works on my late model stuff told me that our 92 park ave computor had been upgraded at least 3 times already & that every computor that he has seen that was "bought" at a parts store was just a tested used one that checked out ok. heck on one of them he opened it up & found dirt & grease....joe