Originally Posted by
Bianchigirll
you are using indexed housing yes? the housing isn't getting chewed up somewhere is it?
This is an important thing to check. From your description it sounds like it could be a cable issue. Remove the shift cable all the way and inspect each section of housing. Also make sure your cable routing isn't causing kinks which will degrade shifting.
Are you SURE the RD is sitting straight? You mentioned straightening the hanger. If it's not straight it could cause the jumping you describe.