Hey Harborman - It sounds like you may have a couple of (intermittent ?) fuel injectors that leak or bleed off when you're parked. To start off - you might install a pressure gauge in the right hand fuel rail to test your static pressure.
It's kind of a pain but if you pull the injectors with their rails up out of their sockets as a unit - then jumper across the fuel relay plug to run the fuel pump and pressurize the fuel lines - you can visually identify which ones are leaking. Don't forget to look at the cold start injector as well for any seepage.
One other suggestion - You can also static test your injectors individually using a "Home Made" tester. You will need a New Long Neck Rubber Tire Valve and a pressurized Can of Fuel Injector Cleaner with a red nozzle straw attached. Remove the plastic cap from the air valve and drill a tiny hole in the cap slightly smaller in diameter than the red nozzle straw of the fuel injector spray can. Insert one end of the red straw through the plastic cap and the other end of the straw into the fuel injector cleaner top spray nozzle. Next remove/unscrew the internal core of the Air Valve. Then pull all the injectors from the fuel rails and remove their "O" rings.
To begin the test push the lower end of the tire air valve over the input side of the injector. A little grease helps. Screw the cap onto the air valve with one end of the red straw inserted through the cap and the other end pushed into the top of the fuel injector cleaner. Finally spray the pressurized can of injector cleaner and look for any seepage on the output end of the injector.
If the injectors need a cleaning - The optional step is to use a cheap-o injector pulser to rapidly fire the injector coil as you spray the injector cleaner through the injector until the injector output end spray pattern is conical. Don't try to trigger the injector using a pair of leads and 12v battery or you'll damage the internal injector coil. The impedance of the coil requires power to be applied only in milli-second bursts.
This is naturally a "No Smoking or Open Flame Allowed" test
Good Luck, Michael