Last year, when I put my car back on the road, I replaced most of the engine management components, including the ICM (Delco).
I’ve had 4 instances - including 1 yesterday afternoon, where either after extended idling or re-start:

stumbles, dies and will not start again until approximately 15 minutes.

On each occasion, ambient temp was 94f+.

Prior to yesterday, I pulled the coil/ICM and cleaned the heatsink, applied Arctic MX-4 Heat Transfer paste AND decided to stand it off from the head (see photos).

Yesterday, several stops temp gauge hovering around 1/4 mark. Upon restart, close to the middle of gauge.
After my last stop, temp in the middle - started, sputtered and died.
Cranking, it “kind of” seemed to fire (always does), but wouldn’t start.
Waited 15 minutes, with hood raised and it started right up.

Does this sound like my ICM is getting hot, then cooling down and working?

I’ve owned this car since new and NEVER had this problem before…

Should I just get another one and “roll the dice”?

 

symptoms are common for failing ICM. What also occurs often in ICM fail is it also takes out coil and vice versa. It is not uncommon to replace both as a pair. People also feel the AC Delco OEM coil is better than aftermarket ones.

 

Thanks. I bought a AC Delco Gold ICM yesterday at Summit. I took the coil/ICM mount completely apart, cleaned it and reassembled with heat transfer paste between all the layers- ICM, heatsink, 2 steel frames and then, paste between the mount and direct to the head.

That MSD Coil was purchased around 2008 - has no more than 3000 miles on it, but still old…

I don’t know what to do to test this, other than drive on a hot day and shut down for 5-15 minutes so engine bay can get hot (conditions of previous incidents).