'93 240 Wagon: 214k miles

(I've posted this before, but haven't been successful yet.)

Can't reset the following codes (unless I disconnect the battery):

2-2-1: Fuel system compensating for extremely rich or extremely lean air/fuel mixture at cruise
2-3-1: Fuel system compensating for rich or lean air/fuel mixture at cruise
2-3-2: Fuel system compensating for rich or lean air/fuel mixture at idle.

Based on your input, I've done the following (with no success in getting the codes to clear):

1. Replaced the O2 sensor. Well sort of. I wish I'd bought the entire cable/sensor part, but I bought the sensor that splices into the existing cable. (keep this in mind)

2. Replaced the fuel pressure regulator

3. Disassembled the air intake tube and found one tiny pinhole, which I fixed with a dab of glue and then wrapped the air intake tube with black electrical tape.

4. Disassembled and cleaned the throttle body with cleaner.

5. Replaced the oil filler cap gasket.

6. Tightened all the hoses and clamps on the intake/air tube assembly. Today I paid $40 bucks to have a smoke test done to identify any air inleakage. No air leaks.

The car runs fine, but the check engine light stays on, masking any future codes (which isn't a good thing). When I disconnect the battery, the computer system resets, and the car barely runs until after about 10 minutes or so. Then the car runs for about 3 or 4 days with this hesitation when accelerating from a stop. After the 4th day or so, the check engine light comes on again and the car runs perfect.

The system is compensating for something that I can't identify. Should I just take it in the gut for buying the Bosch splice-in O2 sensor and go buy another sensor with the cable? Should I buy an air mass meter? Are there any experts that can guide me though additional troubleshooting? I'm ready to fix this darn thing and need an expert to guide me through.

Cabbie