if you can wiggle your battery cable it is loose. that is why it is acting the way it is, my LS did the same thing when my dad test drove it before he bought it. the salesman popped the hood, checked the cables, tightened them up, never had a problem in the last 60k miles. battery terminals should be tightened, they are not meant to be loose so much that they can be wiggled, it makes for poor connections.

97 Montero SR w/Mitsu Adj Shocks & Rear Diff Lock ARB Front Diff Lock 4.9 Ring/Pinion 3.15 transfer box 43:1 crawl ratio 2" suspen lift 2" body lift 2" Gas Tank Lift 35x12.5 MTRs 15x10 Wheels Rock Sliderz ARB front bumper w/12k winch Custom rear bumper