got a 2004 librerty and when i hit the gas it drives fine,once i let off the gas i feel the rear of the liberty sway a bit to the right ,the tires and rims are new.this only happends when i stop excelerating and take my foot off the gas.

Better check the bushings in the lower and upper control arms, something is loose and allowing the rear axle tracking to change angles between accelerating and decelerating.
This is dangerous and could cause catastrophic failure and possibly a wreak.
I would get it to a a shop pronto and have it put on a lift and check all the rear suspension parts carefully.
Not a good idea to keep driving it like this!

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05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
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Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
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GM11 Bld.fan/HDClutch
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98 Dodge Cummins 24 Valve

This behavior is almost always the rear upper control arm. The bushings at the ends of it wear out and crack and the ball joint wears out and becomes a pivot point for the body instead of a "yaw" point like it should be.

Like WW said, get it checked out by a shop (including the rear lower control arms) if you're not capable of doing the work yourself. Most people have had poor luck with aftermarket replacements, but I think MOOG is your best bet if you can't afford MOPAR. Anything else is throwing money in the trash. Also, do NOT have a shop try to rebuild your OEM one using new bushings. The OEM boomerang is a stamped metal design that WILL deform under the load of a shop press, destroying it permanently. Ask me how I know!

Also, if the rear lower control arms are bad, there is an existing recall that might cover the replacements for you. Call the dealer to find out if you qualify.

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2006 Limited CRD: Frankenlift II, Fumoto Drain Plug, DIY Stage 1 Tune, In-Tank Lift Pump