My '99 RX300 started having the warm-start-won't-idle problem shortly after running a tank with STP fuel system cleaner because my gas mileage dropped from 18mpg(city) to 14mpg. Local Lexus dealer wanted over $600 to fix. It took me about two hours to remove, clean and reinstall the Idle Air Control Valve and throttle body.
http://us.lexusownersclub.com/forums/index...c=30723&hl= (Big Thanks to GoldenStateSilverSport)
The idle problem seems to be fixed now and hopefully my mileage will increase. :D
