I was just about to suggest that you double check the tranny fluid level. I'm a bit late - sorry.
While you're having the tranny re-done, you might consider an additional tranny fluid cooler. About $50 US. Ask your tranny guy to put in in for you for free. He probably will.
Finally, as the parts for your transmission start to arrive at the shop, call your rebuilder & remind him to put in only Mercon fluid (Dexron III). DO NOT use Mercon V because the owner's manual SPECIFICALLY SAYS DO NOT USE MERCON V. He'll probably be ok with this - the Mercon V is more expensive anyway.
