Please, can anyone help?

I have an A6 2.5 tdi 1998 that is lacking power.
It will only rev up to 2500 revs, I've replaced the MAF sensor which improved the performance a little but the diagnostic's is displaying 00575 manifold absolute pressure sensor - G71.
I didn't think this car had a MAP sensor, I thought they just used the MAF?
I have had a look around the engine and can't find anything that looks like a MAP sensor.

I’ve also checked the EGR valve and the turbo actuator valve which all seems to be operating correctly.

If anyone could shed some light on this fault I would really appreciate it.