L31MaxExpress
I'm Awesome
Tan valves are normal. The darker valves are rich. Its not unusual to have the fueling on one bank be different then the other and have the O2 sensor wrongly compensate when you have a mechanical issue like that, remember there is only an O2 on one bank.
305s actually have 3 02 sensors ahead of the cat. One on each bank and a 3rd one that is in the Y-pipe ahead of the single cat. All 3 are responsible for fuel trims.