96 850 T, overspeeds it's self, then dies
 

While driving down the road (25-30mph in traffic) it will take a fit, and all by it's self decide to speed up. with both feet on the brakes, manage to not hit the car in front, then it dies. Not to start for about an hour. After about 3 hours, finally get it home. CEL is on, one code indicating a lean condition.
I find a bad vacuum hose, fix it, and it seems to be doing ok for now.

Noticed that it now smokes from the tailpipe. It's not oil, or coolant, as those have a distinctive smell. I'm not certian what it is.

any thoughts?

Vacuum leak would explain the sudden acceleration, weak brake, stall, and hard to start.

What color is the smoke?

I agree.....BTW blue smoke is usually oil, black smoke is usually unburnt fuel (as in too rich a fuel mixture) and white smoke (not water vapor or steam from the tailpipe but actual smoke) is usually coolant and water being burnt.