car idle and vibrates at low rpm.

2004 dodge neon it idle rough and vibrates at 500-1000 rpm. I get a p0508 code on the scan. air idle control motor low system circuit.Is ther a test procedure on things to test before I just replace the air idle control motor. And could that be to problem of the rough idle at low rpm. I cleaned the throtle body it did not help. And could the throtle positioning sensor be the problem.