I'm Stumped. Help
Ended up being much longer than expected so TLDR:
Car is diluting oil with fuel and I don't know why. Has a few other symptoms that may be related.
Video is an example of regular idle with no surge as these issues seem to be inconsistent and I am trying to limit running it due to the fuel dilution.
My 1989 Trans am with an L98 is running poorly. My number one concern is fuel dilution, fuel seems to be getting into the oil at a steady rate, but compression tests seem good and it is extremly close to nuetral blow by. It also idles at 1400 rpm until it has heated all the way up. Once it has heated up, it has a surge with an amplitude of about 70rpm, but it doesn't always surge. I think the issue causing the dilution is that it is running rich, even though at idle there is no black smoke, I can smell it, and there is black smoke when revved a little. I can also smell gas when I take off the intake boot between the throttle body and the MAF sensor. This made me believe the fuel pressure regulator diaphragm was leaking into the plenum via vacuum line but it holds fuel pressure when primed as well as holds vacuum. It is also acting normally with fuel pressure while running with fuel connected and disconnected. Here is a list of relevant parts I put on: FPR diaphragm, fuel matched injectors, coolant temp sensor, O2 sensor, idle air control and the entire ignition system. All of these parts have brought the car from not running to where it is now, but it still has thus issue. The throttle position sensor outputs the exact correct range, the MAF sensor was unplugged and the car ran the exact same after a much longer than usual crank period. I have checked for vacuum leaks extensively using carb cleaner and but blocking off all non essential vacuum lines.