Q: The RPM is racing up and down when in park. Dashboard lights come on one at a time and then the car runs badly

Hi there. I understand your situation and concern. Fist we need the codes that are stored when the Check Engine Light comes on. Any diagnostic scan tool should be able to give us the codes that are set and give us the direction we need to diagnose what is happening to your vehicle. The computer and electrical systems in vehicles are more complex than ever and are more difficult to diagnose without the proper tools and training.

With that said, your RPM fluctuation could be the result of an idle control, air leak, misfire, etc.. If you cleaned the throttle body and it worked for a day, the idle air control valve could be faulty and need to be replaced. If the idle air control valve is shorting internally, this could be the cause of the lights coming on.

The transmission feeling like it jumps into gear could be enhanced by the drivability concern and may be an indication of a broken motor mount or broken transmission mount. A visual inspection of the mount bushings should reveal which one(s) are broken.

I strongly suggest a qualified technician perform an inspection for the idle and Check Engine Light to prevent the replacement of unneeded parts. YourMechanic has several available technicians that can assist you with an idle inspection, Check Engine Light inspection, and provide an estimate and direction of needed repair.