By holding it at 30psi for 8 or 9 days you've over-carbonated this beer.... quite a bit. For future reference, consult a
carbonation chart to figure out how to get your carbonation where you want it. You'll need to know the temperature your kegerator keeps the beer at and your target volume of CO2. Then set the regulator to the pressure the chart indicates.
Typically when people force carb using 30psi on cold beer, they do so for 24-48 hours. This gives you a 'jump' on carbonation. The pressure is then reduced to the serving pressure (often 10-14psi) that will keep the beer at the level of carb you want (see the chart).
To fix the over-carbonation you'll need to unhook it from the gas and repeatedly use the pressure release valve on your keg to vent the excess CO2. I've never really done this before, so I'm sure someone else will chime in with more exact info on how much, but I imagine it's going to take quite a bit of venting to fix the over-carbonation.
Also, next time you're at the LHBS you might pick up 10ft of 3/16 beer line to replace the 5ft you've got going. Longer lines can also help to reduce foaming.
Have patience and good luck man. Cheers.