Try this:

Disconnect vac advance. Hold revs at 3000+. Set timing to 33 degrees or so. Then connect vac to ported nipple on carb.

Then see what spark is at idle, and HOW it idles. If the motor is cammed up, it will probably need 15 deg BTDC or so. If it is less, the advance curve will need to be "shortened" (slots welded a bit). Of course, if you have a MP dist from approx 2000-2012 (Accel guts), this is done easily, but the bottom line is that those distributors are basically unuseable for street use. The miniaturized HEI guts did not scale down well, the weights and springs are so light that anytime you are "on the curve" the timing is super unstable.

Any Mopar distributor can have rotor phasing issues. The test: Drill a hole near #1 cap tower, and see where the rotor "is" at full advance (timing light). If closer to an adjacent cap tower (cyl 8 or 2), this must be fixed.

You must also be sure that there's no vac at idle. One quick test: While idling, screw in idle mix screws. Doesn't stall? It is running on the main, not idle circuits; idle speed screw is opening primaries. Need carb mids, usually drilling 3/32" (starting point) holes in primary throttle blades.

Rick