My '90 240DL Wagon doesn't like to idle when it's hot. The problem really seems to show up when the ambient temperature is up there (80 degrees F or more), as well as the car being warmed up. In the past several months, I've replaced the IAC, RPM sensor, fuel pressure regulator, cap, rotor, plugs and wires. Cleared up all of the other little drivability issues, but this one still hangs on.

After doing the RPM sensor and fuel pressure guage, I had gotten 1-2-1 and 2-1-2 codes, but managed to clear them. I thought I had the issue licked at that point, but It's happened again since then. Today, I checked the codes again, and the 1-2-1 code has come back. The strange thing is that it isn't triggering the check engine light, as I am under the impression it should. Or is it the case that the problem is transient, but the code remains in memory? So, it triggers the light as the car is stalling, but then, once I get it to run, the light goes out, but the code stays there?

Anyway, I suspect the AMM, at this point. I've read all sort of stuff on the archives about what to do next, but I wanted to see of I could get some nice, concise poop on the subject. So...

1. Should I bother attempting to clean it?

...and...

2. It strikes me as the sort of part I shouldn't bother trying to junk up. True or false?

Other recommendations would be welcome.

-EdM.
Franklin, MA
'90 240DL Wagon "Lola"
'72 1800ES "Galadriel"