I have an 2001 expedition 4.6 thats giving me a problem. It started with a misfire on #3 and I replaced the stock coil, but I found that the plug was not torqued down it was loose. When I pulled the plug part of the electrode was missing? So, I replaced both and it ran fine for awhile. Later the motor started idling like it was missing and lacked a bit of power. The CEL light came on again and then I decided to bite the bullit and take to the dealer. The mechanic ran a leakdown test and said #3 intake valve was bad as it ran a 22%. His repair was to either replace the cylinder head for 3500.00 or a new engine at 5400.00. Neither option is an option as I am recently laidoff. Is this a true problem? as I see from alot of posts that a bad valve is rare to happen. I have routinly maintained this car as I think this car is great. I have tried seafoam, thinking its carbon issue holding the valve? Also tried fuel injector cleaners in the gas tank thinking its a clogged fuel injector with both not making a difference. I don't want to sell this vehicle but I might have to in the future for fiancal reasons and want to be able to affordably fix it before I sell it (Better if engine runs well). Any suggestions would be appreciated