2004 Galant 81,000, miles 4cyl, replaced plugs. Idles rough for 3-5 seconds when starting cold engine. Idles rough at stop signs with AC on.

Any suggestions?

 

throtttle body could be gummed up not letting butterfly valve move as needed. can clean throttle body with throttle body cleaner. DO NOT let any of that cleaner get into any of the ports in the throttle body, can do damage.

 

Also remember that the IAC motor (attached to the throttle body directly below where the intake hose and throttle body connect) controls the engine response to loads (AC, Turning steering wheel at low speeds, placing vehicle in gear, etc.). You must also remember that if you plan on cleaning the throttle body with a cleaner..especially for deep cleaning, that you should REMOVE the IAC motor FIRST (handle it by the case, don't touch the plunger or inside surface) and remember to get a NEW rubber O-ring after its removed (even if you plan to reinstall the old IAC motor). The ports in the throttle body lead to the sensitive surface and plunger of the IAC motor and it costs a little over $300 to replace one. Remove it by disconnecting the electrical connector first, then unscrewing the 3 screws that attach it. Installation is the opposite of removal once you switch out the O-ring. Good luck.