As far as the TC3 corner weights being off, sounds like something is tweaked.
- If it is a used tub chassis, they can become tweaked partially due to heat from the motor (which may be why the motor mount was changed on the TC4).
- Check to make sure that all of the shocks are the same length, as a shorter shock could create an issue.
- Back out the droop screws to make sure that one is not affecting the ride height.
- Double check that there are no broken parts, bent camber links, binding ball cups. Check to make sure a-arms are the same height on both sides of car. Basically confirm that everything is assembled correctly.
Since the TC3 was designed for heavier batteries, I would expect the left side to be a little light even with a lipo installed. When I was running my TC3 in VTA I took a C-cell battery sized piece of white PVC pipe, used as a battery spacer, and put enought weight inside of it to balance the car.