[Clown 32]

History.
It missed every once in awhile, than later I stomped on it and it backfired pretty loud and blew the 3" exhaust apart where it connects to the muffler, now real loud. It runs and starts but it has low power and idles rough and gets bad bad gas mileage, like it got good gas mileage before....lol It doesn't backfire anymore when driving just has low power and idles rough.

I put new plugs wires, cap, rotor, ignition coil on (acdelco). What else can I check for a miss? The tach is jumping when accelerating with low power. I think the #1 cylinder is not firing. I took the plug off and it was dark black it should have a tan color. I checked the plugs for spark and that was good, compression is 120 in #1 cylinder. Somebody told me to replace the dist.? Could it just be out of time? Could it have a broken valve? With 120 psi wouldn't this say that it is ok internally?

Any advice?

1994 454 3/4" ton ext cab long box - 185,000 miles