it sounds to me you get hesitation when you accelerate but it is running fine when there is very little load on the engine. Pull your plugs and see if they are wet. could be coolant. You have a leak somewhere...You should get the CEL codes if you can. Probably misfire.
Ordered 4/20/2011 - Delivered 4/20/2011
Has a little bit of this, some of that - a happy camper.