happy 2003 sunfire owner

[happy 2003 sunfire owner]

Hello all, we drive a 2003 sf, has 230,000 km's. ac,tilt,auto,4door,white,etc. we drive highway miles every day, 80km's/day, 2400km's per month, minimum. the vehicle performs excellent.
Within the last five months, we have noticed while driving @ 100 km/hr (62 miles/hr) on straightaways, and we drive over very slight repair bump on the highway, the car moves (jumps?) over a little,...I'd say its the rear,...and goes from left to right, feels about 4 inches, and of course now you have moved past the bump and the car corrects again to straight---feels a little like you were oout of control for a sec. I was searching the other day on an unrelated site, and found some one speaking about perhaps rear trailing arms, or the rubber grommets or I can't remember the technical name for the rubber things that are basically like washers. welcome forum input--thank you.
we have replaced the rear shocks and then went back and replaced the mounts, too. at different garges, over a few months.
Lastly, we have had recently, intermittent shimmy at 90-93 km range, and when it does, its not in your head! No snow or ice build up.

 

[melsg5]

What cold tire pressure are you running? When is the last time the vehicle had an alignment? Are the tires worn out?

 

[CatSkinner]

Last possibility would be a loss of counter weight. Had a 72 Stang with after market rims, for some stupid reason, couldn't keep a weight on them.