Hi, I've got a 1990 240 wagon with a 1993 powertrain.

When I start the car it stumbles and stalls on the first attempt (hot/cold, doesn't seem to matter). If I try to feather the gas pedal or even floor it the engine just stalls right out, doesn't even attempt to rev up. So I simply let it die and then start it again, the second time it stays running 9 times out of 10.

While driving down the road if I'm not giving it any gas or just lightly pressing the pedal, I can feel the car surging forward and then losing power and slowing and then surging forward again. If I put the pedal down the car performs just fine.

I pulled a code yesterday, 2-3-1 "Fuel system compensating for rich or lean air/fuel mixture at cruise".

I’ve changed the Idle Air Controller and the Control Pressure Regulator simply because I had spares. I removed and cleaned the throttle body. I checked for leaks in the clean air tube and checked all the connections. I haven’t found any leaks and nothing I’ve done has made any improvements.

Unfortunately, I'm a bit stumped where to go from here. If the MAFS, temp sensor, or oxygen sensor was faulty I should get a code for that. What else is there that controls the air/fuel mixture?

I noticed that my gas mileage has dropped significantly from about 320 miles per tank down to 260 so my guess is that it’s running rich.

Any ideas?