[Kevin'01]

It starts and if I let it idle, within 30 seconds the rpm starts climbing until the wastegate on the turbo activates. causes an idle around 1500. If I tap the brake just barely, then the idle drops back down to 900. Any idea what could be causing it?

DTCS using forscan:
P0263
P0269
P1271
P1273
P0603
P1536
P1780
P0565
C1189
C1446
C1125

Also important to note is that if it isn't warmed up, it wont move. I can have my foot down and it might crawl forward, rpms wont even rise.
When it is warm, it can pull itself, but it can't pull an empty 8k GWR trailer above 55mph.
What would y'all do? Thank you

 

[Hydro]

So mystery truck ? -- is this your 2001 with the bad wiring harness ?
always helpful to start a thread with the year and model, and any major mods / faults -- al little bit of past history on repairs

I suggest clearing those codes and then let's see what is new that pops up

Your idle sounds like someone has connected the high idle feature for PTO operation -- but just guessing

 

[Kevin'01]

So mystery truck ? -- is this your 2001 with the bad wiring harness ?
always helpful to start a thread with the year and model, and any major mods / faults -- al little bit of past history on repairs

I suggest clearing those codes and then let's see what is new that pops up

Your idle sounds like someone has connected the high idle feature for PTO operation -- but just guessing

Not sure if its a bad wiring harness, I already corrected the grounds and loose/cut wires. Just wondering if these issues turn on a lightbulb for someone

 

[NoRalPh]

It starts and if I let it idle, within 30 seconds the rpm starts climbing until the wastegate on the turbo activates. causes an idle around 1500. If I tap the brake just barely, then the idle drops back down to 900. Any idea what could be causing it?

Well, THAT all sounds like the system is working just as designed though...

Depending on the outside temp, that's how it works, the EBPV closes and the RPM increases, to make the engine warm-up faster. Then, if at high idle, you touch the brake pedal, it drops to normal. Make sure the EPBS, and the tube that connects to it, are OK.

Welcome to guzzle's Exhaust Backpressure Sensor Cleaning Maintenance Web Page

That's not the end of your problems though, you are not running on all 8 because you have codes (263 & 269) showing that 2clys on the passenger side are missing. This is most often caused by the UVCH connections at the valvecover.

If you're not familiar with some of these terms, google something like "Ford 7.3 EBPV"

What are you using to retrieve codes with???