Chasing major gremlin, hope this fixes it!

RockinRobin said

That's about the only thing I haven't replaced. Several calls to MSD and they are certain is isn't their 6Hemi controller. Come to think of it, I haven't replaced the ignition wiring harness either, but if they fire fine upto 7500rpm under light load I don't see how that could be it.

Click to expand...

Under heavy load, throttle wide open the cylinder pressures are higher. If t is going to misfire, that is when it will happen because it is hardest for the spark to "jump the gap" with higher cylinder pressure.

Part throttle doing the burnout is different, even if the rpm is the same.

What is your voltage when the misfire happens?