No idea what's wrong with my 1997 Chevy 2500HD

[SinCity3500]

Hey Donaven, let me know what you end up finding out. I'm having the exact same issue after the fuel pump gave out. Replaced fuel pump, and had to replace the ECM as it shorted with the fuel pump (common problem?); after that same as you described. Anything over 30% throttle there's nothing there, seems like misfiring, but no codes what so ever. Going to replace some of the items you mentioned and see what that does.

 

[kauila]

cleaned/inspected injectors

An injector with some of the right-sized rust particles might not be able to be cleaned that easily, and it might still have enough clearance to run well enough at idle. Solvents probably won't clean it out either. That happened to me once and I ended up replacing all of the injectors to fix it. Maybe you can find the bad one (or ones) to replace.

 

[Autry]

Hey Donaven, let me know what you end up finding out. I'm having the exact same issue after the fuel pump gave out. Replaced fuel pump, and had to replace the ECM as it shorted with the fuel pump (common problem?); after that same as you described. Anything over 30% throttle there's nothing there, seems like misfiring, but no codes what so ever. Going to replace some of the items you mentioned and see what that does.

Did you ever figure out the problem mine is doing the same?