ecm is your engine computer, icm is the one under the coils. he was saying look at the plugs for signs of what may be your problem. and just because a part is good doesnt mean its working. i have had a number of times cheaper wires ran worse than the ones i took off.

my 1989 Buick Electra Park Ave , Ultra has 70,641 (original miles) 30 years old. my car runs smooth , A/C still works (cold) the Ignition module, (coil pack bolts to it.). I have a web site that tell you what the build codes that are ones that on your build sheet on the bottom of the spare tire cover.

this is my build sheet my email address is mickey4965111@gmail.com