LAST TIME FOR ME...
What is the timing IN GEAR!!!!
You may have a situation where timing is dropping out when pulled in gear/lower RPM. THAT CAN NOT HAPPEN. Check it to make sure that idle timing is the same reading in gear and p/n.
That much rpm drop is usually from a vacuum leak or timing drop out. That cam and 14-16* idle timing shouldn't drop more than about 75-100 rpm, IMO. 200 is too much for the set up.