code 51/ quits when returning to idle

[professorbob]

Thanks for the rapid reply... I have the front of the vehicle on jack stands, and this may cause the coolant to be off the sensor. I'll check it and add coolant as required.
Regarding the aftermarket TSP... I would rather keep the vehicle as near authentic as possible and was not intending to us a universal unit, but a OEM type replacement just not from the dealer because of the extra expense. This vehicle is all original and has not been modified.
I will check NAPA or O'Rileys to see what they have specifically for this year model. Some suppliers carry the denso units.
Reference the ground check.
Check your grounds, specifically E1 and E2. Also check Vc (should be ~4.8V at the TPS and AFM harness connectors with the ignition on or the engine running).
Are you referring to the TSP harness plug, or at the Code reading terminal?
Unplugging the TSP stopped the cutting off at 2500 RPM and I could increase from Idle to 3500 with no hesitation. Just got to think there is a problem with the tsp circuit.
How would one go about checking the supply harness to the TSP. It has not been changed in any way.

Now that I am able to get the engine to act somewhat normally, and because I replaced the original MAF Karmon vortex sensor with a used unit not from the 89 model year, I am going to reinstall the original unit to see if that improves/or not the over rich condition.
I have read that the wrong MAF sensor can cause an over rich condition.
Your thoughts?