So ive had this problem for a couple weeks now. I think its mis firing when i get up to high rpms. What confuses me is that when its idling and regular rpms, its fine. But when i get to about 3500 to 3800 rpms, it starts to sound like its misfiring, it sounds like a deep popping sound and the truck studders and loses some power. but im not getting a check engine light or nothing electronically thats telling me somethings wrong. Its a 2010 5.4L. I put two bottles of sea foam in it the other day and its about half tank left. I thought it just might be a gummed up injector or something but it seems to be getting worse. Any suggestions?

 

Sounds like weak ignition to me, spark plugs, cops, or dirty connectors.

 

Seafoam is the wrong stuff to put in the tank, the only additive that's approved by Ford is Techron. It's also one of the few that works without risking collateral damage. Seafoam is only good for carbureted engines with no catalytic converters.