I have 98 k1500 5.7L it has a missfire problem nobody can seem to find the cause including me any help would be appreciated!!! IT has a miss at idle and will stumble in gear when you first hit gas then runs fine up to highway speed once a steady speed it has a random miss\jerk..has plenty of power will not miss if you really gas on it..has been in every shop I know of and has had every sensor,dist cap,rotor,wires,plugs,cam sensor replaced no sel no codes Im so frustrated PLEASE HELP IF YOU HAVE ANY IDEAS

 

Sounds like bad gas

 

can't be bad gas its been doing this for 3 years

 

Not being Merlin the mind reader, can you give more detail as in last tune up, plugs ect?

 

Have you a compression test? That would rule out any internal problems.

 

Whats the fuel pressure?could be a poppet in the spider injector assy sticking they make an upgraded version that runs much better