so iv got this 2004 3500 6 speed. no throtle. just idle. ran the codes p2121 and p2127 so i replaces tps/apps witchever one you want to call it. also it is the one under the battery tray. it had a pedal for about 5 min and the dead pedal again, same codes. randomly pushing on the pedal it will work and i have throttle agian but most of the time nothing. any ideas im stuck and dont really know how to test it or where it runs befor or after

 

If you have a spare (new-ish)battery. install it and try again.

If not, remove and insulate the big cable from the alternator and try again ( note, the truck will run on the battery, and depending on the capacity will stop working after some time)