Carbonic Acid taste: CO2 volumes dependent or PSI?

So all 3 beers that I've kegged have had a kind of funky aftertaste that I'm thinking is the carbonic acid (other option is the beer lines, but I wouldn't call it "plasticy"). I lowered the PSI from ~13 to 8, changing the volumes of CO2 from 2.7 to 2.2. I'm thinking that if I raise the temperature from 38˚ to 45˚ish, requiring ~13 PSI to achieve 2.3 volumes, I shouldn't get the carbonic acid taste because the taste should be dependent on the CO2 in solution, not the PSI. Am I correct in thinking this?

I don't know the actual answer, but I agree with your reasoning.