I have a 2001 2500 24v cummins with 115,000 miles.This truck was my late fathers And was NEVER mistreated. My porblem is that sometimes when you start the truck and go to take off , it won't throttle up past a very high idle.BUT if you turn the key off then restart the engine it runs great. The fuel pressure is between 10 &12 PSI

 

Cycle the key on/off 3 times without starting it and look at the odometer to see if there are any codes.

 

could be the throttle position sensor......... is the check engine light on?

 

probably a bad APPS OR VP44

 

Don't use the swag method of repairing.
1) Get a proper scan for codes. The chain stores have loaners. Some mechanics have better scanners. Perhaps they'll give you a deal if needed.

2. Research other suggestions but don't throw parts. One of the VP rebuilders has a detailed write up on his take for VP diagnosis. Apps can also be diagnosed. There are potential adjustments and timbo has an cheaper alternative to OEM.