2002 Dodge Intrepid low to mid RPM rough running

Hi, My 2002 Dodge Intrepid has a 2.7 liter V6 with 250,000 miles on it. At low and mid range RPM it runs rough- stalls out sometimes, and engine light comes on and sometimes flashes. If I press accelerator to the floor the car just takes off and goes GREAT, but anything less than full throttle it just runs really rough. Dealer can't find a problem. Oxygen sensors are new, catalytic converters are new, compression on all cylinders is good, computer is new, 1 coil was replaced (each cylinder has it's own coil), and injectors are new. Engine code was checked and came back as catalyst insufficiency, and 02 sensors 1 and 2, but like I said they were replaced. Please help!