Calorie/Carb Counting for three weeks, eating clean, 1200-1400 per day, egg, chicken, veg. all the good stuff, clean eating. Haven't missed a day at the gym in 10 days. I vacillate between 700 calories of cardio plus weights and 300 calories cardio and max full body lifting, 7-10 machines. I've been reading our resident 'lift hard' ladies and going for MAX weight 8-10 reps, 3 sets.

Then the good old TOM hits gain 3 lbs. Fine, whatever. TOM ended 2 days ago and I am still up 1.8 lbs and highly annoyed about it.

So my questions are: how long does it usually take to flush out the TOM bloat? And, when you are lifting heavy how does that affect the scale?

I think it differs for everyone. My scale goes up 2-3 lbs before TOM and tapers of by -3rd day or so.
On days I push myself and lift really heavy - the scale is up 2 lbs at least the next day and stays like this for 4-5 days. (It doesn't happen on days I lift "in my comfort zone" hehe).
I have to note that my water intake is around 14-18 cups a day.

Lifting weights will cause water retention in the beginning. I'm not sure how long it lasts, it's been a long time since I started. You know that you can't be gaining weight at such low calories for your stats and with resistance training, so just stick to your path, perhaps avoid the scale for the first little while, and keep going TOM, I don't know, I haven't had proper one in over a year.