stall w/ AC, fixed w tightened spark plugs
 

After changing the spark plugs 2 wks ago, I noticed the 18mpg didn't go up to 20mpg as usual. When AC is turned on, the car actually stalled a few times when idling.

I retightened the spark plugs and found them to be very loose. The AC doesn't cause stalls anymore and the idle is smoother. I hope the mileage will go up too - I'll know when I fill up this weekend.

So, those out there with bad idle, changing plugs is a cheap diagnostic. Your plugs can either be foul or loose.

is your BAC valve good???

I think so. Why?

The stall was due to loosing vacuum with the plugs loose.