Plastic/Styrofoam off flavor??

So I have brewed 7 batches now and 2 of my last 3 batches have had a weird plasticy, styrofoam flavor. All of my other beers have come out find and even the batch between these 2 did not have any of these flavors.

I dont taste any of these flavors when I take samples from my primary, secondary, or at bottling, just after I open the bottles.

I looked around and saw that the plasticy flavors can be caused by oxidation, high fermentation temperatures, of can come from plastic equipment.

I have a couple things that I think it could be:

1. The tubing on my mash tun is not hit temp rated
2. These beers have fermented between 68-74. I dont think this is too high tho.
3. When I sanitize my secondary or bottles, there is generally some of my Easy Clean sanitizer left in secondary and bottles. Since the sanitizer works by oxidation, could it be possible that if I used too much sanitizer, the chemicals oxidized the beer, causing these flavors.

I know that my bottles are cleaned very well and there is nothing growing or stuck to the inside when I refill them. Any help would be greatly appreciated!!

:rockin:

my vote is for the Easy Clean. but those fermentation temps are a little high. generally you want to say in the mix 60's. for your future sanitizing needs i recommend StarSan. a little extra StarSan in your bottles wont hurt a thing.