Electrical troubles and the dreaded Reduced Engine Power

[cdwoodward1]

Ive had my 2003 Suburban for about a year and a half now, and just a month or so ago I started having some strange electrical gremlins. Most of the time it is fine, but every couple of days, it goes into reduced engine power mode until the codes are cleared. When it happens, it throws the code for throttle pedal position sensor circuit B (I forget what the P0XXX number is.) While this code is set, I sometimes have an issue with the cluster where my fuel gauge and volt gauge both drop to 0, and their dummy lights come on. This only lasts for a second or two. Possibly related is that my cruise control is acting up and will sometimes cancel when going over bumps or when using the turn signals. 

Some history that may be relevant, I added steering wheel controls to the truck using a junkyard steering wheel and junkyard clock spring.

I also have already gone through and replaced the throttle pedal and cleaned the grounds under the driver's door on the frame, under the driver's side fog light, on the driver's side of the block abode the oil pan, on the firewall above the driver's head, and on the back of the block next to the oil pressure sensor. I also removed the subharness from the throttle actuator control module to the throttle pedal, tested each wire for continuity, cleaned and reinstalled it.

 

Any ideas from more experienced GM people? It seems to me that I could have a problem with the steering column harness or a grounding fault I did not address.

[cdwoodward1]

Update- it's P0220