04 5.4L 3V 160K miles. Truck idles fine at 500rpm but bad vibration at 700-1200 rpms while in park, neutral and in gear. No CEL on. Truck runs perfect at all other speeds. Brought truck to shop and they read misfire on cyclinder 3 so shop replaced all plugs with Motocraft plugs. Problem still present so ordered COP's from Global Automotive. Had same shop install and problem still present. No codes and shop has no other suggestions. Cleaned throttle body and MAFS but no help. Fuel filter changed 30k miles ago. Any other ideas?

 

At 30,000, it's time to do the fuel filter again, but I would also change the COPs, too. Get a set off ebay for about $125. You should also check for a leaky injector, but doubt that is the problem.

 

Looks like he did put a set of Global cops on it.........

That doesn't sound like a misfire to me - it sounds more like something is out of balance - bad harmonic balancer, a chunk out of a fan blade, or something like that.

 

Yep, I missed the COPs. Good point on the out of balance.

 

Broke down and went to dealer. They checked oil and found 5 extra quarts. That would explain why problem started right after oil change. Dealer drained, cleaned some sensors and truck purrs. Original shop that doubled oil agreed to pay for all my troubles. Go figure.