hey guys, i'm new to this forum, but i play to give back..

Here's my problem:
i used to run 10% fuel, then i decided to upgrade. i used about 2 tanks of my buddys 20% and it ran much better. So i go to my hobby shop and buy 30% thinking it will be even better. But i get home, run a tank, 3 minutes in, it starts stalling, and i can't get it to start. I am new to this, anyways, i richened it. nothing works. now i go to prime it, and it's getting little gas, almost like there are huge amounts of bubbles in the line, it looks kind of like the tank is empty, but the tank was full. i put it away. take it out the next day, and bam, it's running pretty good. about 3 mins into it the run, does the same thing. i'm thinkin i have a hole in my gas line or somthing, but then i figured it wasn't because it works, until the engine gets hot. i let it cool for 15-20 mins, runs good for the first 3 mins. Does anyone know what's going on? i was thinking i might need a cold glowplug, but i don't know.

Thanks in advance!