Power Valve Saver

Could it be that you've got the wrong power valve installed, so it opens up at idle? Did it ever work right? There's info on the holley site that explains how to figure out what PV you need.

For checking vac leaks, I always used starting fluid. Water as mentioned earlier seems A LOT safer though.

Yes, count me in among the tortured ... my GTX breaks down about every other week. It's so consistent that I haven't had to time even pull the cover off my Dart, or do anything toward getting the engine in my Duster. :(