1980 Jeep J-10 seems to be missing or out of time

1980 jeep J-10 pickup 258 mileage: 114,000. My once trusty Jeep haas been sitting for a while now and is badly out of time, or so it seems. It will start, but it misses badly. I cannot even move the truck for it will stall. I have checked the plugs and wires, which were all recently replaced, and even the cap and rotor, which all seem in good condition. Get this, I can even remove one of the plug wires while it is running, and it runs the same! I'm really confused. Any help you can give me would be greatly appreciated.