Hello,
My 901 is the same, 2-3 puffs an then burned taste,
I did take out the material in one cart an wash it, it has some sort of glue/doublesided tape at the bottom (something white), I've lost a piece during washing, but it was so tight stuck in there, now it's less tight and wicks much better, 100% pg, for vg it must be even less tight, so I'll remove up to half of the spongy material from my new carts.
Good vape!
LE: the material in ego mega is very lose, that's where I got the confirmation for it, less material equals better wicking, but beware too light material equals leak, it should not drip when held upside down!