dbull

I just purchased a 91 with the 4.9 6cylinder.I knew it had a noticeable miss at low speed(bucks/surges).After reading several posts here I tried to diagnose my problem as best I could.I filled it up with premium fuel and made a 110 mile trip and it smoothed out and ran like a dream.After it cooled off the same problem returned.Yesterday I pulled the fuse for the tach (on the side of the road) and it smoothed out and has been running great since!My thinking is the TFI module is weak or the heat sink film is dryed out and removing the tach from the circuit allowed extra signal to get to the ecm.Any suggestions or has any one else experienced this?I could also tell it had been to the local ford dealer by all the new parts under the hood.DBULL