At 116K, I can guarantee your swaybar endlinks are shot if they have never been replaced, but that should only be making strange noises, not the symptoms you describe. You may have worn tie rods and/or ball joints--easy to check on the lift (check Haynes manual)and Groton carries both. The swaybars only need attention if broken (rare on front, happens now and then on rear). The IPD upgrade (which I did) gives you less roll on turns. Your struts and shocks are probably entering senility at this point also.

I had to replace a ball joint at about 70K. Last year at about 115K I replaced struts, shocks (and mounts), swaybars and endlinks (with IPD heavy duty endlinks last year). Like a new car, handling is fabulous!
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96 850T, Bilstein HD, IPD swaybars

When you get the car up in the air, check everything! LOL 116K is not much for a Volvo and the parts are pretty solid. There are known failures with suspension bits, however, and you must watch them. If the tires are worn on one side, you will have problems, so check the wear first. The sway bar is a weak point and IPD makes a better than factory part. In fact, IPD suspension parts are all better than factory.
Just verify with a mechanic that a part REALLY needs to be replaced before spending your money.

Klaus
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(V♂LV♂s 1995 854T, 1998 V70R)