3.1 miss fires

Recently I bought a 92 Lumina 3.1 and 131,000 miles on it. Love driving the car, but the engine miss fires at different speeds and jerks the car very hard at times. At idle you can feel just a slight miss. Replaced all plugs and wires, also replaced an IAC sensor. Any ideas on what could be wrong??

check your ignition coils, if those check out ok, could be fuel delivery problem like an old fuel filter or partly clogged injector(s). Probably a good idea to read your spark plugs... if theyre white youre running lean (fuel starvation) and is probably related to the fuel delivery problem I mentioned before. If some are wet, very possibly an ignition problem. If all of them are wet, then its probably sensor failure.

oh yeah....dont forget to double checks for vacuum leaks and the grounds and the usual preliminary inspection.

Believe or not it sounds like the beginning of a cranksensore problem $20 auto zone.