I have a 2000 k2500 with the 7.4(454) it runs good until it gets to operating temperature then it won't get above 2k rpm without backfiring. I have changed timing chain, whole distributor, plugs and wires, ignition control, coil, fuel pressure regulator, and ECM. Any help would be greatly appreciated.

 

sounds like when your engine comes up to temp that your issue may lie in your catylitic convertor.i have seen a bad cat cause the issue your having,once the engine would get up to temp the engine would lose power and do all kinds of weird stuff.i also seen were the problem comes up and no check engine light.by the sounds of it you pretty much replaced alot of key components and are still having your issue.hope this helps.

 

I'll check the cats and see. I'll try anything at this time.