Oh .. for the higher speed I had to align die belt and the pulleys as well as the belt-tension. And I have greased all bearings;-) ..but your printer is using PU-rolls .. isn't it? - have you checked the bearings? Have you adjuste the bearings of the bed in warm condition (heated bed)?
I have tried higher ACC .. but got a lot of ghosting. For high quality prints ACC is about 1300 and max speed 150mm/s. If the surface is just the 2nd rate quality, I can do with ACC 2800 and 200 mm/s.