I went through the same thing with my Dart and thought it might be the PCV valve. Years ago when our cars were new there were specific PCV valves for each car/engine but now the selection has whittled on to just a handful of PCV valves and there is no guarantee that the PCV valve that they sell you was actually set up properly for your engine. Couple that with the fact that your engine is not stock so a PCV valve for a stock engine probably is incorrect either. This is what I came up with for my car. It's adjustable and they give you instructions on how to set it up and make it ideal for your combination. It's not cheap but it appears to work well.
