My stock 86 SVO 39000 miles. I have an erratic misfire under light accel below 3000 RPM that started a week ago. Before this it was purring. I cleaned the VAM and the ducting of oil. I ran codes and nothing showed up. Misfire was getting worse. I measured the resistance on the coil both primary and secondary. Secondary was 35k ohms. The coil was OEM and so i replaced it. Car is running better. Still misfires but not as severe. I bought a TFI and was going to test the old TFI. Upon removal of the old orig. TFI the contacts broke off, no test. This was an OEM motorcraft part. I installed the new TFI, set base timing at 10 deg. with computer out of loop, and checked 30deg with it in loop. Still missing but also a bit better. I started pulling the wires off the dist. with the motor running and cyl. 3 was dead. I got zapped so there is current. I pulled the plug checked gap and compression. There was over 120 psi on 3 cranks. Reinstalled the plug and wires. Inspected the harnesses, did a wiggle test no changes. Next day I suspected that maybe i have a bad injector in hole 3 (these were changed out a year ago with new from Advance auto). Started motor and guess what, misfire is gone engine is idling smooth. I listen to all the injectors with a long screwdriver and i can hear them all clicking with the same frequency. Car warms enough that the electric fan cycles. I go for a 15 minute ride. Car runs great on the way out. Then starts to hesitate under light accel, getting worse. I get back to the drivway and the motor is shaking and missing. I am stumped?