No idea if this could but your buddy's problem but I just battled a year long problem of randomly losing 3000-4500 of RPM on each shift. If I replaced the plugs after every 2-3 runs, it would not happen.
After replacing almost everything in the ignition and electrical system, it turned out to be the intake gaskets were sucked slightly into the ports on 2 or 3 cylinders. It was causing a slight oil leak into the ports which was fouling the plugs. It was also causing a slight vacuum leak and also disturbing the flow of the air/fuel into the intake.