Driving it on a lift and listening with a mechanic's stethoscope to the different possible points will narrow it down really quick.
The really bad wheel bearing on my blue car was actually enough to cause a wobbly/vibratey feeling. For a while I actually thought I had a bad axle because of it. But it was extremely bad, and had been bad for a very long time too:
__________________
'94 Laguna Blue LSi ~159k
.......JDM ultra short-geared 3.900 STi Version 7
6-speed w/ Cobb shortshifter,
ECUtune 244,8.1mm/256,9.1mm i/e cams,
group N motor mounts, '97 grille, JDM clear corners, Momo JDM Legacy GT
steering wheel, apkarian's
LED tails,
silver STi BBS wheels,
PWR radiator,
redstuff pads f/r,
drilled/slotted rotors,
bontragerworks rsb #18, Koni/GC 450f/375r coilovers, Megan Racing adjustable
lateral links,
KMac c/c plates, Stebro exhaust,
ECUtune 1v5, Optima battery in the trunk where it
belongs.
Turbo project
'97 Ebony LSi ~137k #036
.......Power mode mod, JDM clear corners, BBS wheels.
AUX/pocket mod
Now a mod "over
there"
............Photo album