I've found through playing multiple versions of a similar deck that the Blistercoil Weirds are only useful if you are very burn orientated. Sure, they're amazing cards, maybe they've even won a game or two for you, but when do you ACTUALLY find them useful. I asked myself this and came out with the answer of "not that much", so I dropped them (although I've recently made my deck more burn orientated, so they're back in).
I would say keep at least one Hypersonic Dragon. Obviously the Hellkite is better in terms of damage, but being able to boardsweep with Mizzium Mortars at any time is pretty great.
Definitely put Talrand in. I think it's fairly obvious why. He becomes the most broken token generator in an Izzet deck.
To protect creatures, perhaps try Mizzium Skin . Good for protecting Guttersnipes/Talrand AND you get burn/tokens from it.
Also, more Guttersnipes. I see that you might want Frostburn Wierds for defense, but Kraken Hatchling is so much better in that regard.
This is a personal choice, but I LOVE playing counterspells, so maybe put in another Counterflux and maybe replace the Negates with Dissipates, just for more control.
Sorry about the essay, hopefully some of this helped.
November 21, 2012 2:04 p.m.
A month late:Thank you for your advice. It's pretty decent. I stopped playing this deck a while ago and all your advice is sensible. I appreciate you taking the time and effort to help me. :)