My 93 4.9l has miss fired at low idle for some time, and it didn't really bother me, but recently it has got to where it skips while in gear at low rpm (regardless of temp. and speed). The check engine light never comes on. I just recently installed new plugs, wires, rotor, and distributor cap on the truck, and none of these helped. I know for a fact that the wires are in the correct spot and the plugs are in good also. Could it be the coil, it does have almost 155,000 miles on it and I'm sure it has never been replaced. If it is the coil what would be a good one for it, or is there anything else that it could be.

 

Might be a mixture problem. Lean misfire or running too rich.

 

I chased the same problem for years on my 91 f150 4.9. Try using a blankoff plate, or a restrictor plate for the egr tube where it enters the back of the intake manifold. Search all the f150 sites for info and how too. It is easy to do and fixed mine great.