Switched out the ICM and coils with a set from an 01 Grand Prix - no change.

Sometimes I can hear what sounds like a small pop when I stop cranking. I really don't know what the heck is going on now...

Have you checked the compression?

Going to now. Gonna go buy a gauge...

For what it is worth, I had this problem also except the car would die 10-15 minutes into running and not start again until it was cool. It was the crank sensor.

Compression checked:

Front Cylinders:
1 - 175 psi
3 - 150 psi
5 - 175 psi

Back Cylinders:
2 - 150 psi
4 - 160 psi
6 - 160 psi

This was done with the engine cold, since it'* not running :p

I also broke down and bought a scantool - no codes stored.

I talked to a tech at the dealer, and he suggested the next time to do was check the crank sensor as well. I'm thinking it'* either gotta be crank and/or cam sensor, or else it'* the PCM, as I've replaced / verified everything else...

I would lean more toward the crank sensor as that is where everything begins.

Okay, any tricks or tips to give for replacing the crank sensor? According to the manual I have to hold the flywheel in place to get the balancer off...is there a shield I have to remove to get access to it?

Wondering now... would it be worth it to take off the front cover and replace the camshaft sensor and interrupter as well?

Glad you've been able to rule out ICM & coils. Several members here have said the car should start without the cam sensor. Changing the crank sensor should rule out any ignition problems. Did you try getting a resistance reading from the temperature sensor?

PS - sometimes we overlook the simply things. Make sure you haven't mixed up the plug wires.
6 & 3 top coil
2 & 5 middle coil
4 & 1 bottom coil

Plugs are on good. Yay for labeled coils and wires

I didn't try the temp sensor yet, but I'll dig around in the FSM and find out where it is...