Thanks, all. Leak is not the issue, because I checked the pressure actually in the keg using the second gage attached to the in tube (removed the gas line and put gage in its place). I use a 5' 3/16" line, and maybe that is too short. Big head, lots of gas when I pour, but maybe I just lose it because it is coming out too fast. Will give it a try.
When you agitate the beer, it loses carbonation.. I use a 13' line at 14PSI, and it works great.. When I first put a keg under pressure in the kegerator, I shake it a few times morning, afternoon, and again before I go to bed.. I do this for several days, and the beer is usually sufficiently carbed to drink within 4 days or so...
Overcarbing can be cured by running gas at the final desired pressure in through the dip tube and out through the gas inlet (slowly)...... a few blasts of a few seconds each will usually do the trick.. wait for the bubbling sounds to stop between bursts.....
Or you can do it the getto way (like I do) by turning the keg upside down with a party tap connected to the outlet, and then letting gas in at the desired pressure through the gas inlet...
Every time you release some gas via the party tap (which is 'above' the liquid because the keg is upside down), gas is released up through the beer from the bottom, agitating it and releasing gas from it up to the desired pressure... So you release some gas, wait for the bubbling to stop, release some more, wait again, etc. a few times, and your beer is then perfectly carbed...
This is a great technique because it allows you to fast carb a beer by push 40PSI or so into it while shaking the crap out of it a bunch of times for a couple hours or so, and then bringing the carb level down to the desired amount within a couple minutes..
I've gone from un-carbed to ready to drink (with a pre chilled keg) in less than two hours using this method....There's a thread somewhere on this site detailing all this with pictures....
Kind of a PITA, but it works.. Eventually, I'll rig up a separate regulator with a beer out ball lock specifically for this purpose.. Then I can just hook gas up to the beer out, the regulator with a valve to the gas in on the corny, and let it do it's thing...
That's where the real money goes with this hobby.. all the little special purpose 'make it easier' accessories...