Hello. I’ve had my 88 dodge B250 for a year or so. Replaced many new parts. Somewhere along the line something messed up.
Symptoms:
starts great cold. Once it warms up, if I plunge the throttle quickly it backfires(occasionally) but when I rev every time it will drop to about 4-500rpms then iac will bounce it up to 850 back down to 750. I’ve had times where it will die when surging down. Also drops down to 400 once I put in gear and goes up to 600 after.
I figure it might have to do with something electrical. I bypassed one of the wires for the coolant temp sensor(not black n blue). So when it warms up I flip a switch to turn off the coolant temp sensor. It will run beautifully, no low drops after revving, but also idles higher at about 900-1000. Feel like that makes it run slightly rich, but engine is full power.
also coolant temp is usually around the first mark after c. After a min, with engine off, key forward, it’ll show in between 1st and 2nd line. But not while running( might be separate issue)
but if I try to start after when hot WITH coolant temp, it will take a couple tries to start up. With cts OFF, starts right up at idle.

new parts: fuel pump, filter, pressure regulator, fuel temp sensor, injectors, lines. rebuilt throttle body gaskets, new coolant temp sensor, iac, map, tps, coolant temp sender, brake booster( had vacuum leak), distance sensor, 02 sensor, thermostat. Spark plugs, wires, dist. Cap and rotor. Egr, pvc valve, full exhaust
Anyway I don’t know where to start. Every time I get some time to work on it I’m stumped. Any help would be amazing

 

Also no codes except for coolant temp sensor. Does have maintenance reqd but don’t have diagnostic tool