Help, my tach only goes up 2K now. It works fine, just that it sits at 2K when it should be 5.5K. Whats the deal?

Probably debree in the tach. It has a large magnet inside that can attract all kinds of tiny stuff. If you can get to the needle, try moving it by hand with the car off. You may be able to move the debree off the scale and out of the way.