Consistently flat beer.. Maybe under carbinated?

your beer is not 38-40 degrees despite what your temp control is telling you.
the first beer is not as cold as the second. the line is warmer than the keg. CO2 breaks out of solution on the first part of the pour and causes excessive foam because warm liquid holds less gas.

check the beer temp in the glass on the first pour. then check the second pour immediately after. if they are not the same you need to keep your lines cold. a kegerator is always colder at the bottom. a computer fan placed strategically will help. sometimes just moving the lines a bit can help.

be sure your thermometer is accurate, to within 1 degree. you need a quality thermometer and not one that you bought at the grocery store 10 years ago. a cheap Taylor dial thermometer that has been properly calibrated is fine.

Cheers.

 

With 6' of beer line, at 37 deg C/14 psi, my Sam Adams stuff was flying out of the tap. Tough to control foaming. I put on 10' and have zero problems. But i knew what my beer temp was and have a decent regulator (now!!). That is where you need to start. Beer temp 1st, then set co2 pressure according to the beer's # for volumes of co2. If you have flat beer after that, the regulator has to be the #1 suspect.

 

Well I think your problem is the temperature. 37 degrees C(elscius) = 97 degrees farenheit!

Adding on to what billandsuz, adding a computer fan will definitely help, but for those that have kegerators with a tower, what you really want is a blower pushing air through a hose that runs to the top of your tower.

 

And I'm a math wizard.