My 05 Explorer has started making like a thumping sound when you let off of the accelerator. It's a slow thump and not loud. Almost as if it's trying to find another gear. If you give it the slightest gas it will stop. Definitely in the driveline. U joints are tight. Any ideas? God, please don't let it be the transmission.

 

Have you checked tire pressures, or shape of tires?
I ask this only because I searched a similar problem last week on my E 450, and it finally wound up being a bad tire

 

Is it 4 wheel drive ?

 

That does sound like a front CV joint in the axle.

 

How many miles on the Explorer?....................does sound like CV joint.

 

cv joint usually is a clicking, or growling when you turn and apply throttle at the same time

 

Charlie, they will also thump when on the pedal or on the brake due to the velocity. Most explorers (4wd) have locked hubs, therefore the front drivetrain is constantly moving. When I pulled my daughter's horse trailer, I would usually lock the front on my 150 and 250. The reason is that it made the steering heavy and I could control the truck and trailer better. It would also let me know if I had a joint freezing or about to fail.

 

You guys know your stuff, think I'll stick around here,