I have a 454mag efi with procharger . This season it is missing and wont pull rpm past 4500 . I changed wires plugs distributor rotor fuel filter but still runs like **** past 3/4 throttle. Runs fine every where else.
any ideas ???

did it use to run past 4500rpm?

yes

What is fuel pressure doing when runs bad?

It doesnt seem to drop at all

Figured it out new ac delco marine plugs gapped to 37 thous . Just happen at 4 grand i was making enough boost to blow out the spark

i am having the same problem. What were they gapped at before? I have a 502 with a side whipple.

Sorry don't remember . Did you get yours fiqured out