The Patriot has a lot of engine braking when decelerating.
Instead of remaining in a high gear or disengaging the torque converter and coasting, the transmission will downshift in the speed range you describe. If you let off the gas completely, the computer assumes you are preparing to stop and so it will use the engine to slow the vehicle. Once you hit about 5-10 MPH the computer will finally disengage the torque converter and you will feel like you are accelerating because the engine is no longer doing the majority of the braking.
In order to coast in the 25-40 speed range, you have to get good at holding the pedal just at the edge of no gas.
If you do a lot of gas-let off-gas you will feel a good deal of "bumping".
There have been situations where there was a problem with the transmission, but that has been rare.
