Engine Performance problem
1987 Chevy Truck 6 cyl Two Wheel Drive Automatic 286000 miles

i ahve a chevy S-10, 2.8 (1987) when i crank the truck it fires up and runs with no problem. however when i come to a stop and i am waiting to pull off i have to keep my foot on the gas to increase the rpms or gas flow in the injectors to keep it running. if not it will shut off. could you please tell mewhat i need to do about this.

also on my a/c/ compressor. when i cut the ac on the compressor comes on for about 2 seconds then cuts off and comes back on again. it does this the entire time the ac is on. do i need to put more freeon in this or is the compressor bad. please help me with this. thank you so much