I have a 1986 EFI 5.0 HO which has a rough surging idle. When the car was given to me i replaced the ignition switch because the car would not stay on unless i pressed on the gas. Then i replaced the spark plugs and the coil and it ran a little better. But the idle speed drops really low every few minutes and idles rough. However when the car warms up it idles a little smoother. Then when i turn on the air conditioning the idle speed stops surging and it idles smoother. I cant seem to figure out the problem. My spark plug wires seem fine but my distributor cap wiggles side to side.