bcleveland

My 1985 Venture Royale with 73,000 k's starting acting sluggish ..Starts up fine and idles fine for a bit then blogs down. Under load it feels sluggish and you can smell unburned gas. At same time the Tach gauge starting working intermitting . Plan on changing plugs as a first step(has new Battery). It was suggested even one bad plug can cause other electronic issues. Is this so?