I have a 2010 platinum 4x4, 6.5' bed vin 1FTFW1EV4AFA36615 that has the most annoying vibration at 15-20 mph and is felt again around 35-40. Backstory on this thing: Purchased at 96K, drove for 8 months until it developed the "clunk" in the slip yoke on the rear driveshaft. Took it to a dealer in november, had the TSB done for that clunk issue, and the transmission flushed as it was at 106K. The clunk was fixed, but now when it shifts to second it vibrates (like a slipping/shudder). Being under extended warranty, I took it to our local ford dealer who diagnosed it as a bad transmission... most likely from the flush that the other dealer did. The warranty covered a "used" transmission which i was red-hot mad about, but that's all they would do. They also flashed the TCM with the new program..

Here we are a month later, and the trans is great, but it still vibrates at 15-20 mph. The service writer blew smoke up my **** saying that the trans had to learn it's shifting and blah blah.. i'm no stranger to ford vehicles, I know it has to learn it's strategies, but it shouldn't shudder!!!

Out of desperation, I changed all 3 U-joints. It got WORSE. Took the shaft to clutch and performance in mobile AL and had it balanced... and we're back to still vib'ing at 15-20 under accel and decel, and even in neutral. I've had 3 big name shops and the stealership look at it... no fix. We've rotated it 180, we've ensured the u-joints are correct, they move free.. I'm lost.

Being that it shudders at 20, it seems to me something would be out of balance, or not straight (driveline was at .005" runout). Has anyone else had this kind of an issue????

HELP!

Ryan