93 dakota 2.5L problems

i have a 93 dakota 2.5L. When drive for long distances (200 miles) the engine losses power, and will not go over 65mph. The engine sputters when i try to accelerate. I have changed the MAP, oxygen, coolent temp sensor. Also the egr valve, thermostat, coil, plugs, wires, distributor cap, fuel lines, filter and pump. At this point I only have a few things to change before the problem is solved. The codes are giving me a 32 (EGR system). I have not changed the EGR sensor or the canister purge selnoid. I was hoping that there was someone that could point me in the right direction because the the sensor and selnoid are pretty expensive and if the was another way to fix the problem I'd rather go that route. If not so be it. Any help would be great. Thanks.

try to have your exaust flow checked
your cat or muffler might be getting pluged up and cause to much back pressure.

the muffler and cat are both new.

kinda a long shot when the fuel pump was replaced was the filter sock on the pump dirty did the fuel tank get flushed (did it need a flush) and could more dirt have ben allowed in the fuel tank