The reason I ask about the motor mounts is that some still lend themselves to movement. I had the JBR 88d trilogy for a long time, car felt much better than stock. After some self debate I switched to the Damond trilogy and no joke, the car had never felt more solid. Shifting, launching, braking, were much better and yes even steering was more stable. Just food for thought.
I asked about the coilover height because if you are too low, it changes the angles of all your suspension arms. It can make them less stable even if you go with stiffer suspension. Bumpsteer being a big one, also bushing bind.
Both sway bars can have preload on them very easily. If you have enough preload, the sway bars will want to fight your steering inputs or even just weight transfer while launching or braking. Combine this with the lowz or a bad alignment and it can make the car feel unstable.
Once you've checked all that, alignment alignment alignment. Running improper camber can cause one side to lose grip or cause uneven steering. Not to mention croaked subframes and bad toe.
It sounds like you've slapped enough parts on your car to have reduced torque steer compared to OEM. If I had to bet, you are just suffering from an unstable ride which could bring back torque steer or cause other instability. Check all the stuff I mentioned and it should help.