If you are shooting better with it off, it probably means one of two things, either it adds too much mass weight for you (or maybe too much mass weight vs your holding weight), or it changes your bow' s balance for the worse...or both.

I also had a few years old hydrolic stabilizer which was noisy. Every time I shot I' d hear the piston move. I' d try a different stabilizer, and probably a lighter one depending on how your bow balances.