I drink 5-7 cups of coffee every day, and managed to drop 40 pounds in my first 9 weeks of Atkins dieting. That's me...like any drug, caffeine has different effects on different people.

Considering that you've been making good progress during the last 3+ months while drinking coffee, I think it's unlikely that caffeine is the cause of your current stall.

Although I am hardly an expert, I would ask if you have added any foods in the last month that you were not allowing before, changed your exercise routine in any significant way, or reduced the amount of water you are drinking.

If the answer to all of these questions is "no", then you may have "fallen out" of ketosis, or gone into "starvation" mode. There are several threads on this board that discuss these issues (and their remedies) in detail, and you can certainly find good information by searching these keywords.

Realize also that the closer you get to your goal, the slower your body is to respond. Many years ago I used a low-carb approach to shed about 80 pounds. My recollection is that the last 10 pounds took forever to depart.