I also have trouble with Momo Racing wheel but different one. When I race in Blackwood it could change its neutral position. Up to 20-30 degrees and even more. I've found in network game it happens about every lap and effect is stronger. Offline effect is noticeable too. I don't have this at dragstrip and in GTR2 game. Friend of mine has Momo too and has this trouble as well.

In attached replay at lap 2 there is visible snake movements at the beginning of 2nd sector and under bridge crossing the main straight.