Completely frustrated, 91 Z, 350 TPI. New coil did not help but old one back, new pickup coil. Original GM module but replaced with several others and no improvements, put old one back. New pigtail wire from coil to module, new ecm but put old back in when problem still existed. Runs fine until engine warms up them slowly starts to breakdown, tach fluctuates, engine stalls. Always restarts but falters and misses. New cap and rotor. Mentally drained!!