3.9 classic, ignition amplifier module

Am about to embark on replacing the module on the side of the distributor due to an elusive hot running misfire. Should I persevere with the tiny screws on the side of it or is it better to take the distributor off hoping not to upset the timing?

take it out in one.leave the screws.

Changed it, started fine, runs a bit smoother with a lower tickover however the dreaded misfire came back again. Seems only to happen just as the car reaches normal temp or when running on the overrun or light throttle. It does not like pottering about in town traffic. Runs fine when up at 50-60. Potentiometer, maybe?