I cant offer any advise but I go trough the same thing (and imagine most people do), Its like some weird phnomenon that when I get within 100k of my PB my heart races and my hands start physically shaking, this no doubt (for me at least) ends up being the cause of my last guy dying.
Hopefuly someone else (as you suggested) can offer some solution to this nervous play. Im also wondering if drinking caffiene effects gameplay for better or worse, but thats for another disscusion.