[mr0077]

Todd, I had similar problems (never noticed the fluctuating timing, though), and it turned out to be a bad cap on the MSD billet distributor...changed that and no more missing out and backfiring through the carb (and VERY difficult starting problem went away, too). Try a new cap, it's cheap...mine was 2 years and 4200 miles old. Let us know what you guys find out.