I have a 2008 Buick Lacrosse with 64K miles...3800 engine. Several months ago drove her about an hour at highway speed. Parked for about and hour, she started and then just quit. car will crank but not start. After some research replaced the Ignition Control Module and all three Ignition Coils. Please note there were no codes whatsoever. Car ran fine for several months, but last week did the same thing. Again no codes. This time i just disconnected the wiring harness to the ICM and reconnected it and it started. I don't see any corrosion at the connector or worn wires..Am i missing something/ Ground? Anybody else have this issue?

Bairplayer

Based on what I know so far about this, I suspect the wiring at the connector for the ICM.

Next time it does this, just wiggle that bundle of wire around a bit and see what happens. Not violently. Just enough to move it around a bit.

I have done this both ways. With car running trying to make it stall. and while in crank no start mode neither way worked.But will try again next time it happens.

Try tapping or add heat.

The harnesss to the ICM connects to your crank sensor and cam sensor and has a ground. the harness plugs into the harness for the car on the top of the engine by the fuel injectors(near the icm)
Whats the condition of this harness from the side of the engine, use a flashlight and take some pictures.
Do you have a tachometer? if so, when driving does it ever just go to zero, but comes back next time you drive?

Id like to see what the live data for the crank signals says