2005 with codes I can’t seem to fix

I have a 2005 and I’ve been getting these codes.

P2121 Accel pedal code
Fan clutch code (forget number)
Turbo overboost code (also forgot number)

Ive replaces the apps pedal, fan clutch, rebuilt alternator, check all grounds I could think of. I’m finally not getting the fan clutch code but still throws the p2121 and overboost, throttle pedal goes to the floor and doesn’t come back till I let completely off. It’s been happening ever since the truck sat for 9-10 months getting the motor and transmission built. Also I put a bd noise isolator on it with no difference being made. Truck has ppe dual fueler kit with 180hp injectors, taterbuilt 67/67, built trans and a smarty s06.

Ive been fighting it for about 2 months and I’m out of ideas. Any help would be appreciated guys. Thank you

Some of those trucks were eating the engine side wiring harness under the AC compressor. It might be worth inspecting if you haven't already.

This doesn't have the engine mounted apps?

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I’ll check the harness this afternoon, and no sir as far as I know the only apps is the pedal mounted one under the dash.

Check the driver side under the battery some odd ball trucks had it under there. Tried getting a boost fooler to eliminate the overboost code?

I’ll check that too, and not yet I haven’t. Is there any possible way the boost code could cause the throttle to go away? I get off at 2 and I’ll check all these things out.

I don't think they are the same issue. Boost fooler would solve the over boost the ECM is seeing and the pedal issue sounds like a bad apps. Over boost is the ECM seeing to much pressure from the modified stock charger.

Check the harness between the head and the top belt pulley. Seen many of them not tied back and run the pulley.

Alright guys I’ll try all this. Very appreciated, and I’ve changed the apps that’s attached to the pedal recently but I could of got a junk Chinese part like usual.