I was re-reading this post and realized I never detailed what went wrong with the Trooper. So for those who want the technical details, the short answer is the water pump went out...on the DOHC 3.2 it is powered by the timing belt, and when it went out, it pushed the timing belt forward enough so that the belt cut an oblong circle out of the plastic cover. Eventually the belt jumped a few teeth, at least on the one bank of cylinders. Meanwhile, antifreeze was blowing everywhere.

The instant the tone of the engine changed my eyes darted to the temp gauge, and it was still in the green but climbing fast, so I immediately pulled over and shut it off. I think I got it in time to avoid fundamental damage to the engine, but the jury is still out until I figure out this running-on-5-cylinders thing (which, as I mentioned above, I suspect (and hope) is an ignition problem due to it's intermittent nature).

So although the repairs were far from cheap, at least I got a new timing belt and water pump out of it... <img src="/forums/images/graemlins/shiner.gif" alt="" />