On my RX 300 (2000) my light came on at 55K. Code was PO 171 Bank one ..Lean. I took the two ducts off the throttle body, between the air box and the TB. I sprayed throttle body cleaner in and around the valve as well as in the mass air flow sensor. Next let it sit for 15 min, then reattached everything. Pull fuse EFI for a few min then reincert. It has been 200 miles w/o any light on and noted better throttle response. Remember when you start the SUV it WILL run rough for a min or two at idle. willo