Long time listener, first time caller...

I have a kegerator with 3 taps. One is commercial beer, one is hard cider that I ferment and keg, and the third is dedicated to cola. All three are Perlick stainless steel, and have beverage grade tubing that I purchased at my local home brew store. The problem I'm having is that my cola always has a very bad "plasticy" taste to it on the first pour after it's been sitting over night. If I pour off a little bit of cola on the first pour, then fill the cup it tastes fine. It only seems to happen with cola. I put one batch of lemonade in the keg and it never had that taste. I also don't have any problems with my commercial beer tap or my hard cider tap. I've cleaned the cornie keg, lines and tap to within an inch of their lives but the taste never goes away.

Is there something about cola specifically that is causing the plastic taste to leach into the cola from the lines? Is there any way to prevent this? Can I use a different kind of line?

Thanks for any advice in advance.