Top End Miss

For some reason, when I saw you mentioned MSD, I was thinking it was a whole system. If you have a stock style distributor, pull the cap, and pull the rotor/center shaft side to side. My brand new MP distributor had a ton of slop, and the reluctor wheel would contact the pickup at about 5,000 rpms. Dead short, bad miss. Sound familiar? Swapped in an MSD distributor, problem solved. If that is the issue, tighter bushings will fix the stock distributor.