Intermitent, stalling and loss of power.

This problem has been happening for about a year, I've took it to several garages, all of which have no clue, they don't see a code so they think it's fine.

So the problem is, when idling the car sounds rough, the revs move ever so slightly up and down all the time by a 100 revs, when driving, I put my foot on the clutch and it can go all the way past idle and just stall at high speeds, seems to be worse in the cold.

Replaced: MAP sensor, O2 sensors, fuel filter, battery, spark plugs.

Checked for vacuum leaks of which there is none, mixture seems a bit rich, manifold holds vacuum at 17 inHg, checked cylinder pressures which are all consistent, I'm pretty much out of idea's, only thing I can think of left is a new idle control valve.