Yeah, most here have mentioned something with the blue puff. I tried something called AutoRX, which many of it's users have mentioned did great things for leaking valve seals, but not for me.

I think it's a design flaw based on the material used to construct the seals...
Recently, the puff seems to have lessened and I'm currently attributing that to the Shell Rotella 5w40 oil I'm running in there now...
Now, the best way to check for coolant in the oil, IMO, is to run an oil analysis. Google up a company called Blackstone Labs, they are who I use and they'll tell you more than you want to know about your oil. Alternatively, if you have a shop, they might have the test strips that can test for ethylene glycol in the oil...not sure what percentage those register at though...
In any case, you need to get that coolant out of there. I'm wary of flushes, either forced water or chemical. You should really change your coolant every two years or so. Just drain and refill...you might have to do this a few times in order to get everything out...
Shaking and stalling...well, tuneup? Water in the fuel? Bad coolant temp sensor? Start with the easy stuff...
Bogatyr