Make sure you've got super good quality lump, and make sure you start with the biggest clumps on the bottom and build up bigger -> smaller. Never dump a bag of charcoal directly into the egg because that'll cause lots of tiny pieces to drop down and keep air from moving around. The more airflow the hotter it will get. When was the last time you cleaned it out completely?
My lump is just hardware store lump charcoal. You wouldn't recoginze the brand as it's a Canadian manufacturer but I do like it a lot. It could be moist, it just sits in the garage though. I hadn't heard about piling big to little. Sounds messy but I'll give it a try. And I do probably need to give the thing a thorough clean out. I suspect that there is a lot of small chunks that have fallen down as it's been used.
I light it with bbq lighter fluid because that's about the only option I have and let it burn open for a while to get things heated up and the fluid burned off.
Do you use the daisy wheel when you ramp up the heat or do you leave it right open? I'm using the wheel swung wide open and the bottom vent wide open.