HobieMarty

I've been doing a few things to the RX300 "Elvis" lately to make him more drivable as my daily transportation. The front wheel bearings had been groaning for quite a while now, several years in fact, so I finally replaced them. Now he is all quiet at highway speeds. I also replace the ball joints as well and that took care of some very noticeable vibration and shaking under braking. Now on to other issues.
I have always noticed a slight vibration under acceleration when cruising on the interstate and want to address this issue. It is not a misfire or engine performance related, could I have a slightly bent axle, or possibly a worn engine or transmission mount causing the vibration?
also I have a consistent 420 code and I'm wondering if this could be caused by a catalytic converter needing replacement? Let me know what you all think about these issues and as always thank you for your suggestions and input.

maxSteel

for the P0420 check for exhaust leaks