On my 1989 244, which I just got running after buying it for "scrap":
It runs fine when the engine is cold. But yesterday I took it for an emissions test. The test has the back wheels on rollers, and it puts the car in various driving conditions while analyzing the exhaust. It takes about 5 minutes, and they had to run the test twice due to a glitch in the testing machine.
The car ran fine the whole time, but failed the test due to high NOX. I know that the idle air control valve is sticking open, so I'm going to replace that.

However: when I started it up to drive home from the test, the car would barely run or accelerate at low rpm. It sputtered and stumbled so badly that it sounded like a car that "runs on" after it's been shut off. Hitting the gas just bogged it and killed it. It would start ok, and run ok in "park", but as soon as I put it in gear, and then it died.

I found that if I could get a little rolling momentum, and keep it in a low gear, that the engine did ok up in high rpm range. So I drove home in 1st and 2nd gear, and tried to do rolling "stops" at lights.

I know it needs a new IAC valve, and I've got that ordered.

It just had all new plugs, wires, cap, rotor, crankshaft position sensor, (used) coil, ignition module, fuel pump, and fuel injection relay.

I dont' see how an IAC valve could cause this. Maybe the knock sensor isn't working once the block is warm?

What do you think? Any other ideas?

thanks in advance,

bob