Hello, Tony.
I changed the MAFS in my diesel i30 a few months ago because of a rough idle and intermitent limp mode. It would "kangaroo" at times, but only when the engine was cold. I used an aftermarket unit and, at first, it did make a difference for a few kilometers, until the ECU learned the new part and the engine started acting the same. I did get an EGR position error too, though.
After changing a few more parts in the EGR system, the symptoms are still there.
A new idea a mechanic friend gave me is that the DPF might be melted inside, thus restricting the exhaust. Sometimes it doesn't throw a code, but it does decrease turbo compression and forces more exhaust gasses through the EGR system. It chokes the diesel engine, basically. I need to make time to disassemble the DPF and visually inspect it, in order to confirm this theory.
However, it is a very low chance this is what is happening to your car.
Might be the MAFS, might be the turbo pressure sensor (TPS)... Are you sure the car doesn't throw a check engine light, at all?