my truck goes to a idle at half throttle until I release the throttle
 

I have a truck I built from a 2003 dodge 1500 4x4 that I put the running gear out of a 1992 1st gen Cummins and transmission in and have drove for some time. I recently had a leak at the head on my injection pump so I replaced the seals and reinstalled my pump and at first it would rev full throttle for about a mile and now it won't. I have checked my connections and lines etc but once you hit around half throttle it idles but when you start releasing the throttle it picks back up but still will not accelerate past half throttle so whats going on I hope its simple and thanks im new to all the websites

Any help on the subject? It has the ve pump fuel screw is turned a few rounds fuel pin is shaved down timing advanced star wheel is maxed and smoke screw im also running the wh1c turbo boosting 25-30lbs and I do have gauges so I can keep up with heat etc. Just can't figure out what is going on with the fueling now I had no problem before

Thanks for all the help everyone NOT I picked this site bc it seemed to me that y'all knew your stuff but I haven't had a reply