Make it a constitutional amendment for Congress to no longer have to pass raises for themselves. Congress representatives should be paid a percentage of their States GDP that is reasonable and equitable across all 50 states.
I would recommend a flat standard rate across the board, even if it means that some members would currently experience a significant pay increase, while others may see a pay decrease.
They can not form a party fund or PAC, because the end goal of this legislation is to tie a representatives performance to the well being of their States, thereby creating a co-dependant relationship and reinforcing the ideals of a representative Republic.