Shifting into Drive or Park and close to stalling question

I am a total newbie to the world of Rodeos/Passports. I own a 2000 Passport with 57,000 miles on it. I have noticed that when I take out of park and shift to either drive or reverse there seems to be a loss of power. The car stutters like it's going to cut off. It picks back up and returns to normal. What could be the problem?

I checked the FAQ page and search for other threads about this but could not find anything. Sorry if this subject has been talked about before.

thanks!