Idle drop by 500 rpm?

You think not enough timing could cause a 1200rpm drop from park to drive?
I don't think so, but maybe.
I tend to agree, but until it's eliminated as a suspect, I'll be sumbitch if we'll ever know. It's called diagnosis. You eliminate one system at a time. I've been doing diagnostic work on carbureted and distributed engines for over 40 years. There's a procedure. I tried my damndest to outline it. **** it.