My 240 was running and idling really rough so I went through the usual suspects trying to find out why. Leaks , IAC, injectors, ignition, etc. Well I finally found out what it was. My two year old battery was weakly turning the engine over for the last month each morning - but every day it started and got me home from work. It finally went dead and I ended up replacing the battery. That was the answer, the car idles and runs great now. I'm thinking the computer was not getting enough voltage and causing all kinds of idle and rough running issues. Just a reminder to rule out your battery when troubleshootng these types of problems.