94 5.2L Magnum running rough

You have a crank sensor in the bell housing behind the right head, and a cam position sensor in the distributor. I would check that. I believe the cam position sensor generates the pulse for both the timing and the injector pulses, the crank sensor tells the CPU which cylinder is at TDC since it's sequential injection and not batch fire. A bad MAP sensor (or the little rubber elbow) can also cause a too rich condition that might foul out a plug. Does it use oil? The "keg" intakes have a bottom plate which develops a leak over time and causes a vacuum leak into the lifter valley. The injection system can only compensate for just so much. Cheap fix, but a PITA to pull the intake.