What kind of spark plugs are you running? I have Champion RC9YC plugs gapped @ .038 How do they read? I don't know. The 2" headers make it a hand burning experience if I wanted to check them after a WOT run. Are they fouled? No, they are actually cleaner that they ever were with the old cam. I am going through a similar problem with the 383 in my Road Runner. The problem ended up being a vacuum leak in the intake valley pan. Interesting. Maybe I'll recheck mine. Recheck yours carefully. Does your vacuum guage hold steady at idle or is it moving slightly around?
