Is there any way to reverse the carbonic taste on the beer?
Yes, get the excess CO2 out of the beer. An easy way to do this is turn the gas off. Then open the keg vent until gas stops rushing out. Come back and do this again the next day and so on. You can draw beer while this is going on. It will continue to come out overcarbonated for the first few days but eventually the gas will have left the beer and been vented from the headspace. When the beer gets to be about where you like it put on 8 psig for dispense. After a week or so the beer will have equilibrated to the 8 psig setting and at that point you decide whether it is carbonated enough or not and adjust the CO2 pressure up or down from that point.
How do I keep a keg available to dispense without getting to overcarbonation?
. Store the beer at a temperature and pressure that gives you the number of volumes you like.
The volumes of gas dissolved in beer are approximately
=(A4+14.695)*(0.01821 + 0.090115*EXP(-(A3-32)/43.11))
where A3 is the temperature in Â°F and A4 the pressure in PSIG (this can be pasted into an Excel spreadsheet as is. Put the temperature in cell A3 and the pressure in A4. For 35Â°F storage you would have 2 volumes at 5 psig, 2.5 vol at 10 psig and and 3 volumes at 15. The number of volumes which is over carbonated is up to you to determine. For a British ale 1 is considered about right whereas a Bavarian Weizen might go as high as 3.
Is my temp too low? causing too much CO2 to dissolve? If so, what temp would still give enough pressure to dispense without over carbonating
You can play with the formula to answer that question depending on how many volumes you want.
There is another question to be dealt with, however, and that is of balance. The amount of CO2 in the beer depends only on temperature and pressure. Having determined how much pressure gives you the volume you want at your available storage temperature you must then pick a line length and diameter that gives you a flow rate of 2 Oz/sec at the tap. The websites that sell draught beer equipment all have tables of pressure drop per foot at this flow rate for various tube ID's. If you have keg pressure of 8 psig and a drop, in a particular tubing, of 0.5 psig per foot you would need 16 feet of serving line.