car hesitates then shuts off if a/c is on.

Sounds like your idle air control is bad? The idle air controller sets the idle higher when the air conditioning is running.

Yeah. I took the air intake system apart and discovered massive carbon build up underneath the buterfly valve and with the Idle air control valve. I cleaned everything with intake cleaner and reassembled. I drove my car 40 miles in 112 degree heat. The car ran great!!! However i did noticed that when I came to an abrupt stop, that I heard a squeeking sound for about 1 second when the a/c was on. I hope thias solved my problem. Thank you for your help. SHould I have replaced my intake gasket?