Surging occurs when the idling speed is too high or there is a vacuum leakage to the intake manifilds.
The hose that you dis connect is for the MAP sensor and if remove would cause idling problems or black smoke from exhaust.
Check coolant level.
Check for clogging of coolant hoses to IAC and the FITV ( part that is partly hidden in picture, with 2 screws on top. Remove the cover and ensure there is no vacuum leakage when engine is at operating temperature.
Ensure idling speed is adjusted correctly.
Monday, February 7th, 2011 AT 8:49 AM