Help with engine codes

[ScoobyJD]

22Throttle position (TP) sensor – voltage low


44Oxygen sensor (O2S)/heated oxygen sensor (HO2S) – mixture lean


54Fuel pump circuit – voltage low


1994 GMC Sierra SLE K1500 5.7

What could the causes of these codes be? The codes are active after about 5-7 seconds after start up. The truck jumps to 1500 rpm and after about a minute drops to between 1000 rpm to 700rpm. I have also noticed that going into second (auto) the truck shifts pretty hard but goes away after it gets up to temp.

I just recently replace the TPS, IACV, completely new fuel system from tank to front lines (yes I remembered to bolt both ground straps), rebuilt tbi, new oxygen sensor, distributor, plugs, wires, both coolant temp sensors, water pump, thermostat, coolant flush, power steering pump, alternator.

 

[ScoobyJD]

Bump!

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[someotherguy]

Check all grounds under hood. I've probably posted the locations about a dozen times, but,

1. At and next to thermostat housing on intake
2. Small ground off battery to fender
3. Braided strap at rear of passenger cylinder head to firewall
4. Braided strap from same spot on firewall to frame

Richard

 

[ScoobyJD]

Check all grounds under hood. I've probably posted the locations about a dozen times, but,

1. At and next to thermostat housing on intake
2. Small ground off battery to fender
3. Braided strap at rear of passenger cylinder head to firewall
4. Braided strap from same spot on firewall to frame

Richard

Yeah, i had planned on getting to those at some point; lol.

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