I have a 99 F150 with the 5.4. It idles fine but when you are driving down the road it has a miss. No check engine light. I am not sure what to do? Try and scan it at Advance Auto? I don't know if it is a plug, or a wire, or a coil, or?? A local auto repair shop said $78 just to look at it. I would rather not pay that much but if I have to....

 

I think paying that $78 for diagnosis is worth it.

Being that you can't determine the steps to diagnose a misfire, troubleshooting will end up costing you more money and wasting your time.

Ps. Scanning for stored codes would be the first thing to do, kind of a no brainer.

 

yeah get it diagnosed, $78 aint bad, down here in Texas we need to pay $110 just for a diagnosis. but i had the same problem but with my 4.2. so i changed plugs and wires, just to be safe.