[racecougar]

I can say that it is definitely not fuel pump related. You can clearly hear the pump prime and fuel return to the tank from the return line with every turn of the key. It receives fused power through a relay.

I had the "trunk" open when this was occurring, and had a helper turning the key while I listened, just to verify that all was good with the fuel pump.

Just to rule it out, I'm replacing the crank sensor with a new AC Delco unit next weekend.

Dad is also heading to the junkyards this week to try to find another throttle body, TAC module, and pedal (fingers crossed). My line of thought with those is to swap them onto the truck to verify that they work, then swap back to the current parts, and stick these spares in the toolbox. If/when this occurs again, I could swap these parts on and see if the problem is remedied.

The tachometer movement at KOER is definitely tied to throttle position. It doesn't do anything unless you're moving the pedal. I wonder if the TAC module is creating a noisy signal back to the PCM?