This sounds like a possible broken VB spring or contamination in the fluid hanging valves to me.
It seems to erratic to be something normal wrong.
(If you know what I mean by that :-))
Could be something like a broken spring. Cause it seemed to start doing this all of a sudden.
As for the fluid, it looks super clean on the dipstick, and the 1/2 quart that I drained out looks very clean as well. No visible contamination of any kind in the fluid.
