I have a 2003 Bonneville SLE with about 150000 miles. When it is hot it starts idling high pushing the RPMs up to over 2000 w/o touching the gas pedal and begins to shift very hard. This only happens when it is HOT! I have replaced the throttle POS sensor, Manifold Pressure (MAP) Sensor, Coolant Temperature Sensor and flushed the radiator. I have also replaced the PCV. I know I should replace the MAF but it pretty pricey and I am unemployed at the moment.(I did bypass it as I read about and it did not fix the problem) Also pulled the EPC valve and compared it to a new one and see or feel no difference in the spring back. Was thinking it may also be the transmission solenoid. But I don't know much about it. Anyone have ideas?
Thank you all