2005 Ford Expedition • 90,000 miles

I been having a problem with my 2005 Ford Expedition Eddie Bauer 5.4 L.

Engine suddenly starting running rough. Will only idol for a few minutes then start to stall. If you hold gas pedal down some, it will sound better but feels like a cylinder miss. Also motor sounds a little louder than previously.

Replaced fuel filter - no change to performance
Replaced all 8 spark plugs and boots/springs. - No change to performance
Did not change coil packs.

Scan code from local garage says advanced or retarded timing. My dumb fault I did not get the exact code from them. They said that oil sludge may be blocking a VCT solenoid and recommended a complete motor rebuild for $2500 to remove all oil sludge. I'm wasn't totally convinced that's the problem, but I did the following anyway.

I checked the resistance on both VCT solenoids and they both were 8.3 ohms. OK, I think, per other internet searches.

I then ran Gunk oil flush through motor for 5 minutes, replaced the oil and oil filter, per the instructions. I used Mobil synthetic oil.
Still no change to performance

I also read online that the tming chage could have jumped a tooth. How realistic is that to happen. Any ided what it may cost to have that fixed? Or could this be another issue?

November 19, 2012.

Have you checked for simple things like a vacuum leak? There is a hose in the rear of the TB that has a 90 degree bend in it. They are known to go bad and cause a rough idle.