I'm late to this thread but I'm experiencing similar symptoms:
> "When I get off of the gas, the nose of my car (TR6) dives to the
> right, back on the gas and it straightens out."
I've traced this to a poorly mounted, and worn, steering rack. It's
easy to check this, just open the bonnet (hoot) and turn the steering
wheel while watching the rack, if it moves it's not mounted correctly.
If the rack is not rigidly mounted it will move as power is applied and
removed. The rack clams should be mounted using a special compression
tool, however I fitted solid mounts which simplify the fitting process and
remove all rack movement. I still have a minor amount of unwanted
steer due to the rack being worn bit it's much better.