Please help wiring and sensor nightmare

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FishPony

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So i bought a 1995 c3500 7.4 454 tbi. I have several pictures posted below but the trucks symptoms are as follows. Truck starts fine and idles but once i put it in gear and press the gas pedal it stalls or tries to stall out. I bought it with a bad transmission and installed a 4l80e from a 2000 c3500 diesel. I read on here that the converter should still work even though its not the same engine. I have also changed the plugs, cap and rotor. Another thing i read on this site was that the coolant temp sensor can make the truck idle incorrectly and stall so i changed that as well. I noticed there are many plugs with nothing to plug into on top of the engine. Alternator has extra wires hanging out of it. There is a coolant sensor on the passenger side head with a melted plug and harness. I have read that this controls the fan in front of the radiator but that fan turns on still. It might be for the gauge since my gauge is not working? I have a strange suspicion this 454 does not belong in this vehicle since i even tried to purchase and idle air control valve and every part store was giving me one with two screws to hold it down and mine screws in as u can see from the pics below. Any info will be greatly appreciated.
 

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FishPony

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Here is the picture of the coolant sensor. 1/2” pipe thread. As u can see it has two wires going to it. One green with a white stripe and one LIME green looking one. Every sensor i look for only has a one wire plug and 3/8” pipe thread. The drivers side has another sensor with one black wire coming out of it heading to a plug attached to the back of the alternator. All seems fine but gauge does not work. Also note: there is a plug just sitting on top of the valve cover right behind the ac. No where to plug into.
 

Schurkey

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Verify fuel pressure.

Connect a scan tool, find out what the computer is trying to tell you.

Assure all the usual "tune-up" items are adequate--cap, rotor, plug wires, plugs, air and fuel filter, PCV, cranking compression, etc.

You'll need a service manual to identify all the mystery wires 'n' connectors. The four wires spliced with red butt-connectors are suspect--those splices aren't weather sealed. Likely corroded internally.

I can't think of anything in the alternator that would be connected by one wire to a sensor on the driver's side cylinder head. The sensor in the right head near the #1 exhaust manifold runner should power the dash temp gauge.
 
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