I had a diesel shop install a 275hp injector & a 4in exhaust on my 02 with an auto trans. The truck ran perfect before going to the shop. VP-44 & lift pump only have 3000 miles since replacement. From day one since they did the work it surges & dies when you put it in gear & just isnt smooth, even driving down the road i can feel it running a little rough. I took the truck back to them & they checked the inj pump (no codes) & lift pump (tested good). (and charged me for it) They are still talking Vp44 & lift pump but the truck ran perfect when it went there. Any sugestions? I have another set of HO 245injectors that are good, how hard are they to install doing it myself. Or does the computer need reburnt to match the new injector?