how can i tell/find out if my engine comp is bad?

ive got misfiring, irradic idle, very high idle, sometimes doesnt start, or when it does it dies instantly

the fact that it's misfiring sounds like an ignition problem obviously, so you might well be on the right track, but I seriously doubt your car would start at all if the ECU (engine computer) was bad. It's probably your wiring, check to make sure there aren't any stray/loose wires floating around. That's just a guess, so I'm not sure what could be causing that, but I can tell you that it's ignition simply put: missfire=ignition problem. Now you just have to find out what it is, but replace your ECU as a last resort, those things are EXPENSIVE.

the computer is 120.59 so im not worried about that

i have gone through numerous times looking for wires that are loose and shorting out, but have found none