1997 Acura 3.0CL V-6 Automatic- erratic idling

I have a 1997 Acura 3.0 CL V-6 Automatic with approximately 176,000 miles. Bought car used in 2005 with approximately 136,000 miles. Check engine light was on with code P1491 EGR valve-taken to Acura dealer-had EGR valve replaced, ports cleaned. Significant repair history since ownership- replaced timing belt, distibutor cap, spark plugs and wires in February 06. Replaced starter in September 06. Rebuilt transmission in July 07. Check engine light came on again in October 07. On 10-18, my boyfriend checked out the engine to see if he could find out why the engine light was on. The battery was unplugged and subsequently the check engine light went out. We drove the car about 100 miles without incident. That same day, my daughter while driving car, experienced when idling, idles up and down between 1000 and 3000 rpm. When releasing brake pedal car will move on its own without applying gas pedal. Took to mechanic and code read P1491 again- is this possible? Stated it was "searching for idle" and stated that the EGR valve needed to be serviced that the ports were blocked. This doesn't seem logical to me. What else could the problem be? I drove the vehicle again on 10-19. Drove for awhile before this condition re-occured. Have since parked it awaiting EGR valve service on the 24th. Did we erase the actual problem code when the battery was disconnected? Could this P1491 code that showed up be from the previous incident in 2005? I'm thinking it's the Idle Air Control Valve (did some research). Anxiously awaiting a reply prior to the $500 repair.