74 blown 302 w/MSD 6k chip. Took car out for a short ride Sat and it started breaking down @3800 rpm. Almost like it hit the rev limiter. I had just added 5 gals of cam2. Really bad , but runs fine under that 3800. Maybe a problem with the boost retard switch? We were under the dash last w-end pulling some stereo stuff out and rewiring the head unit.. Tried disconnecting the auto meter tach , but same thing, no difference. Anyone have any thoughts? She was blasting just fine before.. and I don't think putting 400 lbs of stereo gear back in the trunk is the answer