Hi there Mate I just recently got into sim racing on pc, due to picking up dirt cheap G923 and VR headset. ACC,Racing Room - just worked and worked great.
But when it came to AC I too felt the FFB was not right and I tried LUT - I basically then just left it alone the last few weeks due to not getting it to run right (like yourself). I then got told a couple days back NOT to use it with the 923 and just use the in game/content manager settings.. I'll be honest - not had much time spare, but I been taking a car and just putting settings to zero and slowly bringing them up - till it starts to feel like I'm driving a car and not some disconnected box that just shakes, spins and basically feels SO BAD. So ATM the best advise I can give you if forget the LUT and work on car till that feels right and then try to set up a few profiles to say have a racing, drifting, etc etc. Hope that some help.. PS as I said I'm very new to this, but I feel it what is working for me.. (I hope!!) Happy driving