While your at it, clean your throttle body and plate, and also the PVC valve and hose. Chances are that you have not been using synthetic oil, and you should be. The reconstituted oil vapors condense in these areas, and cause idle problems as well as power loss and fuel mileage loss. Also, check that the auxiliary PCV hose has not melted down and rotted the vacuum supply. If you happen to spot any rubber vacuum hoses that have collapsed, replace them. Power wash your entire engine compartment. After you have solved this problem, install a set of Bosch Platinum or Iridium plugs to get improved power and MPG's Good Luck!!!