I recently bought a 1999 Concorde LX, 2.7L engine with 138000 miles on it for my son. It idles perfectly and runs great (mostly), but it has one problem. When accelerating, the engine stutters between 2000 and 3000 rpm. If you slowly accelerate and keep the engine rpm under 2000 while it shifts, it does not stutter. When revving the engine in neutral, it stutters at roughly the same rpm, but not above or below that rpm range. At cruise speeds, it runs fine as long as the rpm is outside of the 2000-3000 range. There have been a couple of fault codes set, namely P0352 coil #2 and P0432 catalytic converter #2. Once I cleared the codes, they sometimes come back when the car is driven at highway speeds for around 20 miles. I replaced the #2 coil, I also replaced the Throttle Position Sensor as the voltage did not increase smoothly with opening of the throttle. I confirmed the fuel pressure remains at around 55 when the engine stutters and holds pressure at least 5 minutes after the car is shut off. I checked the Intake Air Sensor, and according to the Haynes manual, it is in spec as well. I put new spark plugs in the engine. I cleaned the throttle body and replaced the upper / lower intake plenum seals and the EGR / Plenum seals as well. Finally, on the advice of a Chrylser mechanic, I replaced the PCM. Nothing has had any affect on the stuttering.

I'm at a loss for what to do next. What should I look at?