Wallace,
Thanks for the feedback. My engine is a Ford racing crate motor M-6007-XE3M purchased in 2006. When I googled timing for that part number, I got Ford Racing Performance M-6007-X302 340 hp Crate Engine Guide. That document states "Timing: 14 to 16 degrees initial, 36 to 38 total with carburetor". I am running a Holley Street Avenger 570. Since the M-6007-X302 replaced the M-6007-XE3M, I assumed that the timing should be the same.
I will try backing off the timing to see if that helps. I will also start to look into the carb to see what I can find.
Thanks again.