Car stalls and cuts off

I purchased my 2001 toyota camry (2.2 L 2164 CC L4 5SFE DOHC)a year ago. About 6 months ago, it started stalling, shaking, and cutting off when coming to a stop or making a turn. The brakes also seem to go out when it is stalling & cutting off.
After sitting for a while the problem goes away. It might not happen again for another month. I took it in to my mechanic and he did a diagnostic check and found nothing. He replaced the spark plugs, wires, fuel & air filters & put a fuel inj. Cleaning kit in. The problem continued & he replaced the air fuel ratio sensor. The problem still exist. The only thing I noticed is that it always
occurs within days of filling up with gas. He
also checked my car for bad
gas. I have spent more than $1800.00 to fix this problem and it still has not been fixed. Is there anything you can suggest that might solve this problem. Thank you in advance for your help in this matter.

Teresa