Well, here's how it goes. My engine has been making a sorta weird rattling noise when I accelerate lately, so I decided to upgrade to premium. And that has stopped that problem.

The only problem I notice now, however, is that I'll start up my car and it will want to die, so I rev my engine a few times, get above 2000 rpms, and keep it there for about 2 seconds, let it return to idle and it stabilizes to where it won't die then. This problem only started when I upgraded my fuel though. I don't know if they are related somehow, but anyone have an idea on what it might be?

 

Make, Model, Engine size, Trans type, Year?

Little more info please.

 

Sounds like you have too much advance. Check if a timing spring hasn't broken in the distributer and reset the timing considering the timing chain may be worn or has jumped. Check hoses for vacuum leaks. Set carb throttle plates to idle position and air bleed screws to approx 1 and a half turns as a basic setup. Possible leak in power brake booster diaphram.