I had a faucet drip in my bathroom sink. I determined it was the hot water (confirmed by the warm drip and it stopped when I shut off the hot under the sink). I assumed that the stem went (which happened before, to the cold stem) but after replacing it and tightening everything, I still have the drip. Can I assume the faucet needs to go? It's an old Price Pfister.
Note: The plumbing and shutoff valves are new but the faucet assembly is old.
There should have been a 'packing' in the stem assembly. This is usually a gasket or a series of gaskets that prevent water from seeping around the stem when the stem is in the off position. If the packing was in good shape (no cracks or brittleness) and was seated properly then I would say it's time to replace the whole fixture.
In my past experience if the leak doesn't come from the stem or the packing around it, then the time finding the problem and the cost to fix it usually is not worth it for a cheaper fixture.
Replacing the stem assembly complete with rings/washers etc should have solved your problem. Did you carefully check the bottom seat and assure there was nothing stuck to it or if it was cracked or worn? There were a lot of different seating arraignments on these older sets. I have to say however, most Price Pfister models are not high end quality even though they have a good warranty. You can fuss with this thing, but if you don't find the problem easily and cheaply, bite the bullet and go with a new higher end Delta or Kohler fixture with ceramic cartridges.