214k miles '93 245

After the battery has been re-connected, the car runs for about a week and then throw out the same codes ... the codes are associated with the fuel system compensating for extremely rich/lean mixture at cruising speed and idle. (can't remember the specific numbers...but it's the same ones over and over again.) I replaced O2 sensor, replaced oil cap gasket, found lose hoses and tightened, removed air tube and cleaned the throttle body, removed air idle motor and cleaned, replaced one broken vacuum line going to the emissions charcoal canister. Afterwards, I tried resetting the check engine light using the diagnostic thinga-ma-giggy (socket #2), but the check engine light immediately popped back on when the car was started. I then disconnected the battery (thinking that the system had a "memory")and the car ran great without the check engine light for about a week...THEN, wa-la, back on again (same codes). Can't figure out what keeps throwing the codes.

I need to get into some more technical troubleshooting....but I don't want to take the car to the auto repair....I've always worked on the 240s and have experience doing the timing belt, struts, ball joints, water pump, etc. I think I can fix this thing if I could only figure it out. Can someone provide me a good plan for diagnosing this problem? Again...the codes are like 3-2-2, etc....the ones associated with fuel system compensatng for extremely rich and/or lean mixture at both cruising speed and at idle.

Cabbie