89 Straight 6 w/ 5spd & 180k miles

It idles fine, but as soon as I let the clutch out one of the cylinders starts to misfire.

It misfires whenevers their is any load on the engine whatsoever, even just maintaining speed, anything other than neutral.

At first it only did it when I was accelerating hard, now it does it all the time if its not in neutral.

Is their any electronic way to tell which cylinder it is thats misfiring?

Will the "running codes" show this?

It doesn't misfire when idling, only when theirs a load on the engine...will the "running codes" still show the misfire? (I can't exactly check the codes while driving down the highway)

 

Sounds like the timing is off.

 

Might check and or change your fuel filter and ignition componets (plugs, wires, etc). A fuel pressure check might show something, also.
Good luck.

Roger Carter

 

have you ever looked under the hood when its running in the dark. Could be plug wires arcing. I've had this occurrance, when popping the hood when it was dark out the problem became very apparent.