First let me say the 2000 Excursion V-10 has been a fantastic vehicle. I use it heavily in business and tow trailers continually; up to 7500 lbs frequently. I have full lube completed every 3500 miles. I just bought a second Excursion (2005) V-10 this week and take delivery in January. History of problems with the 2000 Excursion: At 75,000 miles the electronic shifter failed costing $275.00 to repair. At 95,000 miles I blew a spark plug out and fortunately a Ford dealer put in a helio-coil for $515 rather than replace the head. At 125,000 miles the electronic door locks gradually quit working. The locks are my single biggest complaint. They are junk. At 145,000 miles my mass air sensor had to be changed at a cost of $159.00. Total repairs to date are under $1000 not counting the annoying locks. At 149,000 miles I am noticing fluttering in the transmission in high gear at low RPM's. It dissappears if you push the accelerator causing it to shift down. The flutter returns when it shifts back into high gear and is worse under load. This is not a complaint. I have worked this machine very hard. Is there a simple repair or am I into a new transmission. The engine runs great and burns about 1 quart of oil at about 2500 miles. I want to keep this truck running. Any ideas on the transmission before I take it in?

 

Nice history. The locks are a pain is the neck. They do all seem to go out at the same time and there is a service bulletin about it. Need to replace all actuators at one time if the truck is under warranty and one at a time as they go out if it isn't. (just replace the ones you need...)

Your main problem though, doesn't even sound like transmission troubles to me by what you describe. Usually, tranny problems start with a delay into gear, or slipping while accelerating. Seems like a misfire problem. See F-150 or Expedition forums above this one. 6.8, 5.4 and 4.6 all use pretty much the same ignition/fuel systems. Maintain your trans but don't invite anyone into it 'til you know for sure its a problem. Check the basics first.