95 Vision TSi code 12/51/77

I know the 12 is normally the battery and the 51 is lean fuel mixture due to rich correction facter and the 77 is the S/C speed servo issue. I got the 77 once before and replaced the input speed sensor because the car would't shift beyond 2nd gear. Now i have it again. The 51 blows my mind. I just replaced the fuel pump, fuel pressure regulator and had them clean the injectors as well. Anyone know the fix on this. I don't think the fuel rail is leaking because there is no noticeable leak or smell of fuel.
Anyone have any thoughts here?