check ur charging system with a volt meter. 12.5 to 12.7 with everything off, including the engine. 13.3 to 14.5 at idle is what ur volt meter should read at the battery. 13.3 is on the low end of the scale and 14.5 is on the high end. sounds like r alt is going bad or u got bad connections since u say it starts fine if u wiggle the battery cables.

do that and let me know what u got.