Why does engine die at idle, sometimes when you press gas, sometimes while coasting? on 1997 Chevrolet 1500 Pickup

Been in a complete circle in exhaust system 2 years ago: replaced Cat converter, O2 sensors, ERG valve, fuel pump, various hoses. Now same thing thing--it dies while idling: we've replaced fuel pump & filers, ERG valve, a vacuum hose, cleaned gas tank plus used B12.

Asked by for the 1997 Chevrolet 1500 Pickup
check the IAC (idle air control valve) this is located in the throttle body , this should fix your problem
2 more answers
Is the check engine light on? Did you do any computer diagnostic? Any trouble codes in computers? What is the fuel pressure?
How about spark plugs and the rest of the ignition system? When where they replaced last time? What brand?

you also may have to clean the throttle body. they are known to get dirty and cause stalling at idle. just make sure you use throttle body cleaner and NOT carb cleaner. carb cleaner is too harsh and will take the protective coating off.