For the last 3/4 weeks my car hasbeen doing the p0300 code thing, have replaced wires/plugs/icm. Local shop did this work and problem went away for a few 100 miles.
The last time it started doing this I turned off and restarted and while it started was running rough same as before only this time it was blowing white smoke out of exhaust pipes
is this a sign of my uim and or heads leaking water into cylinders, no water in oil and far as I can tell not low on water or oil in water. Any idears the shophas no idea

 

low on water? check ur coolant level

 

Real quick, I'd do a visual check of all of the vacuum lines running into the TB.
You should also be able to hear it whistling under the hood if it's a vacuum leak.

That would cause a rough idle and misfires, and it's real quick to check.

-Riggs.