2006 Commander vibrates when letting of gas, please help!

[Commando]

I have a 2006 Jeep Commander with 78,000 miles and just today(11/21/2011) it started vibrating when I let off the gas pedal. It doesn't do it when I gas or brake, but when I let off it shakes and makes a bumping/fluttering type of noise. I tried putting it in 4 wheel low since it's always in 4 wheel high(I think) and it is even worst. Please help steer menus the right direction, this is my only vehicle. It's a 4.7 v8 by the way.

 

[Bounty__Hunter]

Sounds like a bad ujoint, most likely in the rear driveshaft. I recommend inspecting all the ujoints.

 

[Commando]

So I woke up this morning and for some bizarre reason the vibration is mysteriously gone???

 

[eric m]

If it was me i'd still crawl under there and check everything out...you don't want to be replacing something on the side of the road...trust me.

 

[TerryMason]

My CJ7 did that on the high way one time. I'd stay on the gas and it was fine, but when I'd let off the Jeep would shake. I pulled over and found that the right rear wheel only had two of five lug nuts left.

When you check the ujoints, also re-torque your lug nuts.

 

[Commando]

It came back last night. How do I go about inspecting the ujoint, and how much would it cost to replace?