2004 Dodge Stratus Slow to go

If the car is in park I can step on the gas and the engine revs up as it normally would. If I have the car in drive, lets say at a stop sign, and when I go to take off if I give it too much gas at once it "chugs" along - almost as if it's not getting enough gas or maybe even too much. No matter how much I step on the pedal it just wont go - no increase in RPMs - nothing. If I dont step on the pedal too hard and slowly accelerate this does not occur. Once I get going down the road there does not seem to be a problem - the vehicle will still run at highway speeds with no issues.