I would like to start with stating, I am no pro, but the symptoms you are describing match something that I experienced about a year ago.

You stated the ICU was replaced, but did not state a reason. When the ICU is replaced it is very important that you renew that heat transfer paste under it, some Indies just knock it out of the way. ICU's are heat sensitive and that paste does make a big difference in the ability for the ICU to shed heat to the fender well.

Hope it helps.

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1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K