idle stall out

[craig57]

I have a 97 doge caravan sport 3.3 liter
i just recently increased the antifreeze to 25 degrees below down from + 10 degrees
it ran fine at a idle before
since i have added the antifreeze it now starts to run rough once it warms up and latly once warm the idle gets very erratic and evently shuts down
i cant understand how the anti freeze would affect this
im thinking a sensor of some kind, vacume leak or in worse case the idle postioning unit
Has any one else had any simlar problem? and if so can u please shed some light on this for me.
Thanks and merry xmas