My 4.6 L engine has ran rough almost like a cylinder wasnt firing. The check engine like hasnt come on, but when I did have a misfire some time ago it was very similar to what's going on now. I have 97K on my truck.
Does anyone know if the exhaust manifolds dont hold up, and could be cracked which is causing the rough running. The only reason I say that is I can hear the engine running more so in the cab. Has anyone had a problem like this. Changed out fuel filter, and recharged air filter and new plugs at 55K.

 

I changed my plugs and wires and 105,000 due to rough idling and then a couple weeks ago it started to run rough again and then the check engine light came on so i went to autozone and they tested it and said that cylinder number eight was misfiring and i changed the plug and it runs great now and it has only been like 8000miles since i changed them i have a 97 f-150 4X4 4.6L try to see if they can test it for you and tell you what is wrong. This also just happened to my uncle in his 2001 F-250 4X4 5.4L this past friday