Throttle position sensors

Tedmeister

I have been working on a track Z that someone else started and did most
of the work on. The car has had codes P0603 (ECM back up circuit), P0223
(accelerator pedal position sensor 2 / switch B and P0122 (accelerator
position sensor 1 / switch A). The car got an ecutek tune through the previous
owner. One mechanic said not to worry about those codes. The check
engine light would come on and off by itself periodically. Since it is a track
only car I cannot drive it far, unless I'm on a track. Had my first track day
with the car a month ago and had four sessions with no issues, went
back the following day and the car would rev from 800 to 2200 by itself instead
of idling. Called it a day and spent the next couple of weeks prepping and
then painting the car. That issue went away, but I took it in to another
mechanic, who said it would need an ECU update through nissan, but said
the the car could be taken to the track as is. Went to another track weekend
and half way through first session the car went into 5mph limp mode.
Code P2138 (accelerator pedal position sensor circuit range/performance).
Cleared the code, cleaned the MAF sensors. Unplugged the throttle plugs and
sprayed with cleaned and reconnected. Ran a session with no issues. Next
session after two laps check engine light came on, but no driveability issues.
Called it a weekend any way. I've read that it could be a range of issues,
including tire and wheel size. Suggestions as to where to start would be appreciated. I don't want to just start replacing components, such as pedal
assembly, and hope I fix it by sheer luck, since I'll have to go to the track to
test out any of the fixes.