Missing at operating temp

[jerry mize]

I have 97 has vortex 350 this this ideals smooth and runs great until it reaching normal operating temp then goes to crap starts shuttering and missing unless you stomp it the it opens up and moves on I've tried mass air flow, intake temp , throttle body the truck has brand new distributor, new crank senor , any help would be awsome as the truck is not popping any codes

 

[Cadillacmak]

Do you still have the black box computer?

 

[isd503]

I had a similar problem with my 1996 GMC truck. It turned out there was a part of the wiring harness from the engine to the transmission that was exposed and bumping up against the metal undercarriage when I got up to a specific speed. In my case, the engine wiring harness itself had to be repaired