You say you have this car completely tuned. Did this happen before you added any tuning parts? If not I’d say your suspension is set too low.
This car is one of a few cars I’ve found where you can set the suspension height so low you can’t steer it if you have it lowered all the way (or even close to it) because the wheels are so buried and trapped in the fenders. Not sure why the game allows it (maybe for pictures?), but this car you can set ~20mm lower than you should be able to. If you have this car lowered all the way, or really close to it, then even setting shocks and springs to hardest/highest setting won’t help you.
Most times this only happens under braking conditions where the front dives and it traps the wheels, preventing steering, but the Amuse S2000 front wheels will be trapped even when coasting if height setting is low enough.
I believe the lowest I’ve been able to set mine without having any steering issues at all is 110mm or 112mm and with that I had to set my shocks and springs both at max. I believe I currently have my front set at 115mm.
I haven’t driven this car in update 1.31 yet, so maybe the suspension or physics changes have negatively affected the suspension on this car even further from what I posted above.
I‘d set the suspension height to at least 115mm and shocks and springs at max and see if that helps. Then you can go lower/softer if you wish until you encounter the issue again then you know the limit.