2002 Dodge Intrepid Engine Stutters around 50-60 mph

The car starts and runs great. It accelerates smoothly if I push it right up to 60 or 70. The problem is that once I reach around 50mph and am driving along it starts to kick and sometimes will downshift into 2nd which feels like I hit something. I have to feather the gas or slow or accelerate to stop the jerking. The problem does not occur if I leave it in 3rd. There is no service engine light or trouble codes.