Hey guys, joined the forum because after doing a lot of searching, most threads did not have an outcome to the persons problem.

So here is where im at. 2004 f150 supercrew 5.4l bone stock. Just turned 225k miles and has been a really good truck. All maintnence done regularly by myself.

TPS and fuel filter last replaced about 6-8 months ago, throttle body removed and cleaned at that time also.

Truck ran great until 1 month ago, began missing at idle very noticibly but did not throw any codes for about a week. over 1k RPM or at speed it is not noticable, gauge still reads 16MPG as always. No CEL at any point during that week. CEL finally came on, read the codes and it showed 0307 and 0316.

Plugs were old so i replaced all 8 with Motorcraft 515's. Used anti-seize on the threads and was careful to not get too close to the tip. Replaced all 8 boots/wires at the same time with dielectric grease. Cleared the codes.

No improvement at idle at all, CEL came back on in a few days. same codes.

Cleaned the MAF sensor and pulled the "PCV" tube from the intake and cleaned it. Replaced the COP for cyl 7 and cleared codes. No improvement.

Few days later, CEL again with same codes. This time replaced injector for cyl 7, cleared codes, no improvement. CEL back on, same codes.

Sorry for the long post, but i've run out of ideas and am thinking a compresson test is next. Truck does not smoke at all, no erradic noises either. Might be a little of the "diesel" noise coming from the cams/phasers, but i would think that would throw additional codes if that was the issue.

Thanks in advance for any help!