i have a 1988 z24 and on it it is the round plastic piece connected to the throttle body by two "torx" head screws, one hint the throttle body is at the end of the air intake hose.
You do not adjust the Idle Air Control as it is controlled by the computor.
Somebody please answer if you know
You can not adjust the idle screw, it is sealed off at the factory. If you are having a high idle problem check for a vacuum leak or a bad idle air control valve. These will commonly cause a high idle.
It should be at the base of the throttle body.
Check your idle air control valve
check your idle air control valve and/or your TPS
Yes, I have a 1988 and 1989 Chevy Cavalier Z24 and they both have the 2.8L V6
The heater valve is in line in the heater hose from the top back of the 350 engine about half way to where it enters the firewall to connect to the heater core. The valve has a steel wire control cable connected to the top of the valve control lever. It has two hose connections, one in from the engine and one out to the firewall core entry point. Trace your heater hoses and look for the metal valve with the spiral covered control wire.
valve cover
Could be EGR Valve.
1988 chevy cavalier flasher take ash tray and bracket out look up and lift you can see it if not you can put your hand up in to lift and find it.
in the fuel tank