Stalling at Idle/Low RPM's-2000 Max

At 65K original miles (all but 3 are mine); my Maxima SE started stalling one morning at idle. After restarting, I noticed the RPM's kept falling below the normal 600-650 after it is warmed up when I was coming to a stop or at idle. It was showing anywhere from 200-350 and would just shut off. Attempting to make it to work that morning, I must've restarted the engine like 25 times, some of which while I was coasting (from 20 MPH+/-) or from coming to a stop. I had to drive with both feet, using the brake to slow or stop and using the accelorator to keep the RPM's above the shut off point 400-600. VERY DANGEROUS!!! There was NO check engine indicator until the next morning when I took it in for service to my local dealer. They checked the service codes and came up with one solution, that I needed to replace the AAC Valve (automatic auxiliary control) which compensates for any extra load put on the car (i.e. A/C, Defogger, Headlights, etc) by increasing/decreasing the timing when needed to keep the RPM's at the normal 600-650. The part alone (dealer price...$300) and labor (rip off price...$250). I refused to pay this