I did a lot of reading on this the other night and come to find out I was a wee bit wrong on my advice (don't hear the often do you)
Did you ever say if the Nutter bypass was done on yours? If it's done and all your emissions crap is void you should be running it at 8-10 of timing with your vacuum on a manifold source and here's why. On start up more advanced timing makes it harder for the motor to start so manifold doesn't build idle until the jeepf motor is running. So with a base of 8-10 once it started your vacuum pulls up to 16-20 (should) giving the motor a smoother idle, run cooler and have more power. The higher advance timing doesn't effect the motor because it's not under load. When you step on the gas the motor goes under load and if some timing doesn't pull out you begin to detonate. The vacuum advance on manifold will dive off to prevent this. When you get to cruising speed most of the vacuum returns allowing the timing to go back up and increase effiecency.
On smog cars the base timing will be set lower or even after TDC to help gasses burn cleaner but the power is reduced. When hooked to ported as you apply the pedal vacuum begins to build and advance the timing to help build power.
Honestly I don't think your issue is with the distributor. I think you have a carb timing issue or some other problem.
88 YJ 35's 8.8 rear, family style roll bar, ax-15 external slave conversion, Custom double D fab dash 4" of lift taurus fan, Head light wiring upgrade, MSD 6al, JB conversions SYE, 258 with RV cam, Long tube headers, Borla exhaust. 1"mm, Auto meter gauges.