Ok so.... 94 lightning. New LMR 40 over block. The cam they claim works with the factory emc ( I forget the spec) headers. That's about it. The truck will some times fight the start. Once it does it runs like a champ!..... until you get to a higher rpm. It spit and miss. New properly gapped plugs, wires cap and rotor. Can anyone be of some help?

 

Have you checked fuel pressure?

 

pressure is spot on

 

How about timing? You said it has a hard time starting, so maybe timing is too far advanced. That may also cause the high rpm misfire.

 

I set the timing according to the cam card. I've also tried adjusting it a few times and it doesn't change. Maybe and Injector?