Magdaddy

motor mounts was my first thought, FWIW...If they look original, may be time for RS or Wevo.

993/907

How old are the tires (in years), and how worn are they?

gordo

MarkD

Work your way from the ground up

Since tire pressures are good...
Alignment... And as said in 2005, be sure the shop has a KT tool

Jeff96-993

Also, do the tire swap on the rears. You don't have to go far to know whether it's a tire issue.

When I bought my car it had the same problem. Turned out I had one rear tire that was 0.1 inch taller than the other. Replaced the rears, car drove perfect.

David Schiff

i had a similar problem, was the left or right rear strut collapsing under accel.cnt recall which all the simple stuff was checked before. the Best suspension person I know of is in Castro valley, I had been there b4 and the diagnosed and fixed the problem. 97C2, i willtry to recall his name, but i know bay area folks know him, blocking on the name, K.... something i think
PM me if you need, will get it for you, but other R listers know of him and may chime.

Beretta

Do you have different brands on the front tires vs the back tires?

L23FPorsche

I did find that one of the links in the rear suspension was lose. Also the tire on that side was worn considerably more than the other. After tightening that link, the car tracks straighter under acceleration but not yet normal.