I have a 2003 Ford F-150 Lariat with the 5.4 V8 with 205,000 miles. It overheated once last Fall on my way home and I shut it off right away. I noticed all the coolant was gone from the reservoir. I refilled the coolant and noticed It kept leaking for a while after that. I didn't know where it was going though. No shop could find the leak. I also kept having a code for a Cylinder 1 Misfire. I changed the coil and all 8 spark plugs but the code kept coming back. Finally the shop realized that the coolant must be leaking into Cylinder 1 causing the misfire so I must have a blown headgasket. I asked if I could use a sealer and they said they wouldn't recommend it. I used Steel Seal anyway though after watching your videos and it stopped the coolant leak. I still get the Cylinder 1 Misfire code though so I took it back to the shop to have it checked out. Now they said I need a new engine because Cylinder 1 and 8 are loosing compression and it'll keep happening til the engine goes out. I didn't plan on replacing the engine. I figured maybe the Cylinder 1 spark plug was still wet that's why the truck has the misfire and idling roughly. Or maybe I should replace the Cylinder 1 coil again. What do you think? The truck doesn't run that badly. It's just lacking some power with that misfire.