1996 ford contour lossing power in lower gears

When I start the car, it revs high and then slows down about 30 seconds later. It loses power in the lower gears when I first take off and once I am above 20mph or so it acts fine. Still not as powerful on the upper gears but not a complete loss of power. The problem seams even worse with the AC on.

I first thought it was the transmission but a friend said to check the vacuum line to the distributor. Ideas?