friend brings me his 3800SC Swap (to fix engine "leaks", trans "leaks" & "suspension" work) and it "Idles" at about 1500 (no Vacuum leaks). code reader says "crank sensor", but we put one in about 5 months ago. then the reader says MAF bad, so I took a known good one and tried it. idle came Down, but runs ROUGH. disconnect the MAF and it runs ok, but idles like crap. put the original MAF back in, and sometimes idles high, then low and rough. tested all the injectors for pulses, had new injectors about 1 year ago. Sensors?? ignition??? HEELLPP ! Thanks

[This message has been edited by Lou6t4gto (edited 10-12-2020).]

oh, has 50psi fuel pressure at all times.

Take a very close look at the plugs for the sensors, if the metal female contacts in the plugs are distorted, replace the plugs.

A dirty MAF sensor will sometimes register as lean fueling or defective. As for the crankshaft sensor code; was a case learn done when the engine was installed? If not the timing will be way off.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

case learn was Not done. but that was not it. the large tube that comes off of the throttlebody, originally for the emissions, had a Crack in it with a rubber cup on the end. so checking for vacuum leaks it didn't show on any vacuum lines. right before I was going to call it quits I started shooting "quick start" around everything, thats how i found it, a-crack in a metal tube ! oh well. alls well that ends well.