your a link off on the chain.
I am pretty sure, glowing manifold was the kicker.
the cam not performing as well as it should.
we all noticed a big difference in the low end with the rv cam.

the cam gear mark should be at like 11:45 vs 12:00
as the tensioner takes the slack up on the left, faceing the motor and moves the chain mark up to the 12:00 position.

my bet is you are one or more links advanced on the cam.