I just got a Rebuilt short block installed yesterday and Im having a problem with the Ignition I think. I replaced the ICM and coils/wires. still the same rough idle but once I give it and throttle it clears up. I can hear it misfiring though the exhaust at idle. I pulled off the #1 plug wire and could see it arching, pulled #2 and it would just barely arch randomly.

what is causing my miss? could it be an injector?

Are all the push rods the same length? If not, I know I mixed a couple up when I put the engine back together. Could this be causing my miss?

Thanks for anyhelp