I think that the wording is that it shorts out every other plug firing. Still it does sound suspiciously like an rpm limiter.
He doesn't have a lean fuel problem otherwise it would backfire. More like a firecracker going off. That's what is dangerous. That lean explosion is untimed and will put a hole right through a piston.
He needs to read the instructions on the MSD unit and inquire with the MSD tech people. Unfortunately they are about as usefull as tits on a bull. That company is such a piece of shit it should be banned.
I have a pile of MSD components that I keep as a reminder to myself at how stupid I am. Their stuff is GARBAGE!
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