Hey guys, I have a 83 Bronco with a 302 that once warmed up on the highway will start to sputter it only does it at 70mph and up and when it is at operating temp, sounds like a backfire in a coffee can under the hood. I have replaced the distributor, timing chain, fuel pump and filter and the carb was recently rebuilt. The rest of the time it runs perfect, it starts with just the touch of the key.
Any ideas?

 

Manifold leak generated by increased back pressure perhaps. Hard to be certain but if it runs just fine the rest of the time there are few things that could trigger that kind of behavior. With the engine cold, do a close inspection of manifolds and and gaskets for soot marks that would indicate leaks.

 

Thanks greystreak92 I'll try that in the morning.