Lubemanager

I have an 06 mega cab with an auto transmission. It started to act strange last week. I pull a 7X14 utility trailer, but need to resolve this before I go across the country in june with the 5ver. At low speed, when cold, it seems to hesitate, almost like the engine flooded (like the old carb days). It does this empty, and has started to act up when warm as well. Has any one else experienced this: could it be a transmission or a fueling issue. Tranny fluid replaced yearly, fuel filter replaced yearly (20K miles) It has alway had a small vibration at a idle: dealer could not find an issue. feed back welcome.