I agree with the T-stat.. must have a bleeder hole of decent size (~1/8-3/16").. I recently experienced the same problem... had an air pocket blocking flow after I replaced a lower hose... they apparently don't make many new T-stats with the bleeder hole... they should!

Mopar Mitch "Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers! Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!