I bought this car used with 102,000 miles on it. Several months (and several problems later) my engine started acting up where it would rev automatically up and down every few seconds and this was especially annoying when stopped on the road. Eventually it stopped when I cleaned out the throttle valve with carburetor cleaner but it still happens when I turn on my AC or heater no matter what setting its on. I don't know how to fix this and it relates to another problem Im reporting about the engine stalling.