New Draft Tower Question

Okay - so I've been serving my beer from a picnic tap with 6ft of 3/16" diameter line for a few weeks and all has been good. I install a draft tower and plumb it up, draw a beer and it's all foam. I draw a few more - foam. Also I notice that with the picnic tap, from the first draw, the line was full of beer. Now it's mostly bubbles and after a few minutes, the bubbles settle and it's mostly air.

Any ideas?

If it means anything the keg is almost empty (a little less than 1/3 left) and I had to move it around a bit (in and out of the fridge to cut the hole for the tower... Maybe I just shook it?

I'm serving an Amber Ale at about 12 psi.

Thanks,
Andy

What's the ID of your beer-out tubing, and what is it's length.

I have a 5' beer-out line and I need to be around 8 psi to avoid foaming.

One thing that's probably contributing is that the line in the tower is heating up which forces Co2 out of solution. The other thing is that your faucet is probably a lot closer to the keg height wise than you used to hold the picnic faucet. The different height changes the head pressure.