I have an idle problem. I have a 70 Chevelle with a Quad jet carb and 454 BB and an auto TH400 tran. I need to know how to adjust the idle/air mixture and set the idle speed correctly. I have heard to turn the idle/air mixture screws 2 turns and I have also heard to do it 4 turns. I have tried that and everything in between. I can get the car to idle at about 1500 rpm and put the car in drive and it drops to about 600 rpm like it is supposed to but it starts idling a little lower the longer it sits in drive. Also, while driving, it is surging a little like it is starving for fuel. I have changed the plugs and wires. Any other suggestions? It may not have anything to do with the carb because the carb has been running fine and it is only about 3 months old. I may be barking up the wrong tree by spending so much time on the carb. I don't see any obvious leaks. HELP!!!!