One week ago, car would crank, fire but not start unless gas pedal depressed, then would stall out if foot removed unless allowed to warm up 30 seconds then would idle at 500 RPM. Later, check engine light comes on. (code 6) Car once warm runs and drives fine, I notice when warm and in park, RPM is around 1100 (too high). Mechanic wants to replace throttle body ($1300) and maybe computer. Engine wiring harness has been replaced. What's going on? I can't believe that this has to be a $1300-$2500 repair. Car just passed emissions with flying colors 3 weeks ago.