400E idle problem

[janos_z]

Took my 400E to Canada last week (10 hours each way), and it was fine all the way there, as well as for the first couple days while driving around town. Then one day I pulled into a McDonald's, and when I tried restarting the engine 5 minutes later, the car kept stalling out. It turned over okay, and ran fine if I kept my foot on the gas, but if I let it idle it immediately dropped to 300-400rpms and then just died. It was like that for a couple days (sometimes if I was really careful in letting off the gas, the rpms would stay at like 400-500 and the engine wouldn't die), and eventually the "ASR" light came on too and the car started shifting weird (holding lower gears longer before upshifting). On the way back to the US, I stopped for more gas, and when I restarted the engine, everything was back to normal....

Now the car's okay, but I'm concerned this episode may repeat -- it makes the car pretty much undriveable. But I'm also reluctant to take it to a mechanic since there's no actualy problem with it right now. What could have caused this, and why did my "ASR" light come on? An obvious guess is the idle control valve, but then how come the car fixed itself (for now)? Are there any relays or other electrical pieces that can cause this to happen? Thanks, guys...