I have a 1991 245, ~220,000 miles. Check engine light is on. I went through the diagnostic process per Bentley, and got codes 2-3-1 and 2-2-1. I found a leak in the large corrugated hose from the AMM to the throttle. I replaced every hose I could except the brake booster vacuum hose...that fixed things for a day or two...

Now, I can reset the ECU, and I get the Check Engine light back on ~immediately~ after starting the engine. The car runs OK, except for a slight stumble when opening the throttle when cold. ECU inputs check out OK, except the throttle switch gives a 3-3-2 (instead of the expected 3-3-3) when closing. Testing the switch with a DVM indicates it is operating properly.

My next move is a guess...replace the throttle switch, then maybe the AMM. Before I do that, though, I thought I'd see if there may be some other thing I'v overlooked. Anyone got any other ideas?

Thanks in advance!