:agree2::agree2: never trust the guages, on my blazer the voltage gauge went to about 17 volts, i checked it and it was at 13.something at idle.
I used to stall in idle, heavy traffic, high heat. Our idle is a mechanical adjustment. Idle depends on tranny, engine hot, ac on. I think mine is 780 rpm in drive with brake applied, manual tranny was a bit more. When the oil light came on, I was thinking I was in big trouble, I bought a manual gauge and tied into the oil filter as there was an NPT fitting there, oil pressure was about 75 psi at idle on the aftermarket gauge, shoot well past 150 psi with some go pedal applied. The dash oil gauge is controlled by the computer, so think about it why would it hover aroud 40 psi and jump to 0 psi ? Just check your rpm, or turn the screw slightly, only at about 1/8 turn each time, it does not take much. I think you will be OK as I have never heard of the simple CTD oil pump going bad.i have a '93 D250, straight six cylinder cummins turbo. i hope you're right. as it would cost much less to fix. i'm still looking into acquiring or fabricating a manual pressure gauge to test with. looking for a local diesel mechanic in case the oil pump does appear to be failing. seems that the job is a little beyond what i can in the parking lot of my apartment complex. don't know.
can you easily describe how to adjust the idle?