Stop in for a cup of coffee

Damn, our second car won't start. 06' Buick Lucerne with a 3800. It always starts. It starts, runs rich/rough the idle kicks up and runs on all 6 for 5 seconds and shuts off. Hit the key and absolutely nothing until it sets for 10 min or so and resets. Strange **** going on around here.
Nothing? Dead? Im thinking battery cable issue. I carefully trim off the rubber and clean cable ends. Side post batteries suck.
How is coolant level?