engine misfire 93 grand am

I have a 1993 pontiac grand am 2.3 litre sohc with a serious misfire problem. Originally I thought it was the cat. but was mistaken. I got a code for the iac (idle air control) sensor so I replaced it with no results.
I also replaced the map sensor and eac.
The car will run at idle but when you hit the throttle, it stutters then clears up at high rpm. When you put it in gear and try to drive, it sputters coughs and pops like crazy with a serious loss of power. A friend told me it was a coil problem, but when I replaced the two coils it seemed to get worse (running on 2 cylinders). This is really starting to drive me crazy cause I can usually figure things out. Can anybody help me please??

Before you spend more money on coil parts ect... check to see what cylinders you have spark on. It is a common problem for coil housing to go bad, but don't just jump to that conclusion, If im not mistaken 1&3 run on one coil & 2&4 on the other one. maybe your coils weren't bad after all.

If you still have the problem after you get spark on all cylinders I would go back to make sure you don't have a catalic converter problem, pull out the Oxygen Sensor and see if that changes anything, if it does then its your catalitic converter after all.

If not either one of those I would suspect fuel pressure regulator or oxygen sensor next, but these are just guesses. Maybe someone knows what else is on the list with the IAC error code.

Remember unless you have a good scan tool (like the $10,000 ones that professional mechanics use) you will only see the top item on the list of what generates the error code there may be 5-10 things on the list.

ya, like gmack said. are the wires on right? that'll foul it up. could also be a timing belt, jumped or ready to break... Also pluged up injectores will cause a misfire then the computer shuts down that cylynder or attemps too. May need a reset.

Before you spend more money on coil parts ect... check to see what cylinders you have spark on. It is a common problem for coil housing to go bad, but don't just jump to that conclusion, If im not mistaken 1&3 run on one coil & 2&4 on the other one. maybe your coils weren't bad after all.

If you still have the problem after you get spark on all cylinders I would go back to make sure you don't have a catalic converter problem, pull out the Oxygen Sensor and see if that changes anything, if it does then its your catalitic converter after all.

If not either one of those I would suspect fuel pressure regulator or oxygen sensor next, but these are just guesses. Maybe someone knows what else is on the list with the IAC error code.

Remember unless you have a good scan tool (like the $10,000 ones that professional mechanics use) you will only see the top item on the list of what generates the error code there may be 5-10 things on the list.

Thanks for the help....The quad 4 has the wires right in the coil hsg. so you can't get them wrong...changed the coils fuel filter and plugs and now it runs like a champ.

Alright Rustynuts! Glad to see ya got it running.I've seen alot of Quad 4's with cracks around the plug(S), just around the ends where the spark plugs attach. Oh ya, I forgot about the Q4 having the wires connected to the top cover, Duuh!