[davepl]

Take a look at the underside of your hood over where the compressor sits. I did roughly the same as what you did, and mine would hold vacuum for hours, but when running would throw oil off the snout of the compressor, and that's where I lost all my freon.

I can't speak to whether R-134 will work well with the factory condenser, but it does work well enough with a parallel flow. Now would be a good time to do that if you haven't already.