Thanks Donnie. I did that a couple of days ago,
and I get about 48 PSI on idle, and at full-throttle going up a decent grade I get between 56-58 PSI.

I've changed out the O2 sensors, but I still get CHECK ENGINE light, per OBDII scan, P0134.

Could going to a 3.07 limited-slip diff from the stock 2.87 of the 1995 C36 cause the CHECK ENGINE light to come on?

Thanks,
:-) neil