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Discussion Starter · #1 ·
A few weeks ago I noticed the car "jumping" or "bouncing" while on the interstate. (high speeds only 65-70mph).
Then I didn't notice it anymore and my service engine soon came on. (about a week of the bouncing).
This morning, once I got on the interstate it would buck everytime it shifted gears. and I mean not a slight buck but the kind that would throw you out of the window. In addition there is a humming while excilerating. It's not loud - but I can hear it loud and clear.

Is it the transmission? easy fix? expensive fix?

This car has always been in tip top shape maintenance wise and this is my first experience with ANY problems.
HELP!!!!!!!!!!!!!!!!!!!!!!
 

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could be but first can you give a bit more info please Is your park avenue a base model with the normal 3.8 liter? or is it a supercharged ultra model? The ultras use a slightly different tranny than the non supercharged models.
 

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Could be the TPS (Throttle Position Sensor).

They don't cost much and are only held on by a few screws.

Make sure there are no loose/cracked vacuum hoses and the PCV hose is OK too.
 
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