2004 Ford Expedition Revving up
..2004 Ford Expedition with 65000 miles, a 4.6 engine....it is revving up the motor , RMP to 3 and the check engine light came on. We had 2 diagnostic test done, first one stated the 1 and 2 plugs were running lean, and the 2nd time the oxygen sensors were bad. we had a oil change, replace fuel filter and air filter, idle air control, replaced oxygen senors, replaced throttle position sensor and clean out the throttle body, replaced the PCV hose . The check engine light has gone off but its still revving up . Can anybody tell me what is causing this?