Vacuum reading help.

So I was able to check and adjust the valve lash tonight. Nothing was too majorly out of wack, some were a little tight but feel good now. However, the rough idle and stalling problem remains.

Here's my notes/comments/questions/thoughts:

At idle, my exhaust is a little white. I've adjusted the idle mixture numerous times and saw no change in color, and I've yet to get any black smoke. Something is causing it to run too rich...

With the valve cover off, the white exhaust color went away.
While adjusting the valves, the adjuster screw on the exhaust valve for cylinder #6 felt way more difficult to turn than the others.
I also noticed that there seemed to be a little more blow-by fumes around cylinder #6.

Are these indicators of a sticking exhaust valve on that cylinder?
Faulty PCV system?

Also, idle is much smoother in neutral, and when the engine is cold. And it's most rough and stalls frequently in reverse... Am I correct to assume that with these factors it is NOT an ignition problem?

Thanks!