there's a lot of points to consider with this situation.

1. engine might be defective
2. fuel system might be defective
3. filters might need replacement
4. clutch might be sliding
5. simply lack of warm up

my suggestion:

1. warm up and see if it makes a difference
2. if it doesn't make a difference:

1. bring it to our shop so we can diagnose the engine for you (free, no charges)
2. when driving, try to get a feel on how your clutch reacts when you release your pedal, this will help you determine if it's sliding or not.

be patient, eliminate one possible cause at a time. you will get to the bottom of it for sure.

cheers!