good, bad, ugly

[Money pit Beretta]

Be sure to get AC plugs, others can cause problems. Stay away from cheap wires also.
My bet it that the ICM is bad and you may have a bad coil. That is kind of a normal thing that happens to a 2.8/3.1L. The exhaust manifold is very close to the ICM and can lead to failure sometimes.
My ICM on my 90GT failed around 130k. After two coils went bad(one that came on the car and a new one) I replaced the ICM and the coils. Never had a problem after that. I did use computer heatsink grease on the bracket that the ICM mounts to. It keeps mositure out and helps connect the ICM to the bracket(for heat transfer). You just need a thin coat, spread it with a credit card.
Also use dielectic grease on the ends of the pulg wires. Also the pig tail for the ICM and connections for the coils.
Do not forget to use antiseize on the plug threads! You have to use it when you have aluminum heads. If not the threads in the head may pull out.
If you still have a problem you may need an O2 sensor. I'd do that anyway if you have extra cash. Buy only a GM or Denso.
Chop talking because I'm tired. Sorry about that.

[Money pit Beretta]

Oops I ment that I put the heatsink grease on the metal part of the ICM. Be sure to clean the mount off before you connect it to the ICM. I did front and back just to be sure. Lacqure thinner works well after you wipe all the road dirt off. You can use rubbing alcohol after that on the ICM side if you are a nut like me. Not a bad idea to use the rubbing alcohol on the metal part of the ICM before the heatsink grease.

[ifixalot]

These engines had fuel injectors that were unreliable. Perhaps you have one that is bad.
When you pull the spark plugs, check for uniform color, they should be very light tan and all look about the same.
There is probably pics on the net to guide you.
If you have one that is black, it is leaking, if you have five black and one light in color, then one is not opening and the ox sensor is
enriching the others to compensate. On mine, one had a ohm reading of 4 ohms the rest 11-12 ohms. The 4 ohm coil is what goes bad.
The car has been sitting? Did it sit because they had a problem and never got it fixed?
good luck

[meeksberetta]

Im planning on removing the intake and checking the injectors. It sat for several years so im sure they are gummed up. Ive been running good cleaner in the tank