Looks like after replacing some of these parts, the stumble is better described as a misfire under load when warm which points us back to ignition, low fuel pressure or manifold leak. After ruling out FP and vacuum leak, concentrated on ignition.

Figured out it was a new set of Duralast wires that were bad. Replaced with set of AC-Delco and all seems fine now for the past day or two. Will run it a few more days and post back.

I have used Duralast in the past with no problems. Maybe this was a bad batch. They were routed properly with standoffs. The AC-Delcos are the correct set according to part # but too short and had to route them up against block and exhaust manifold. We'll see how long they last but as of now no misfire.