I replaced the PCV valve and grommet, but it doesn't seem to have improved the situation. My gas mileage is also way down (about 14mpg, usually 19mpg), I assume from the computer adjusting to rich.

Will shops that have a smoke machine (evap tester) diagnose a leak? How much should it run to have hook up their machine and blow smoke in my tubes? I found my EVAP test port over near the battery, but I don't have a smoke machine.