Had to jump back on here and post an update. After 2 months of troubleshooting (and driving) this problem with everyone's advice, I kept having this nagging feeling that it actually could be a 2nd bad distributor cap. I was complaining about that to someone yesterday and found that they had delivered one to my house while I was at work (probably to just shut me up). I put it in and vio`la... Problem fixed!
I can't convey how ticked off I am at this company for cheap crap parts. This is the second time I've had a less-than-a-year-old distributor cap from them go bad in an odd way. The last time resulted in over $1,000 in parts (tows, diagnosis, fuel pump, coil, crank sensor, knock sensor, plugs, starter - my fault, etc.) and this time was over $200. On top of that, my first alternator from them lasted only 3 days before locking up. My first starter from them had bearings grinding and went back immediately. My front brake rotors from them are still warping (with no drag) in 15,000 miles which is about 6 months for me. They've ended my free lifetime replacements (after 5 replacements - but they won't warranty the idler arms that THEIR rotors tore up which are their cheap 1 year pair) now so I'm going with Napa or GM this time. Oh, and one thermostat that didn't want to ever re-close. I'm now wondering how long my half shafts are going to last. I replaced them on yet more bad advice when my transfer case viscous clutch froze up and caused the chain to pop in hard corners.
All in all, except for not standing by their TSB for paint delamination on the hood at 6 years and 6 months (6 months over), I have to say that this Chevy Astro has been pretty dependable. Actual problems have only been an alt, water pump and transfer case clutch. The rest of the problems have all been because I replaced perfectly good tune up stuff at 200,000 miles because I figured it was just time and used crap parts. Not bad for 324,050 miles.