If the car surges under lower rpm acceleration (4th/40mph hit the gas but not floored), change out the ignition wires and plugs, use Motorcraft double plats. I had a carbon track on the number 2 (firewall side center plug). Also, watch out for extra weld on the spark plug "hook" electrode, I had that prevent the plug from threading in! I gapped to .050, a little less than specified. The rust color stuff is probably on your number 2, I saw that too. Grease the boots with silicone grease to keep out water.