Did you ever find a cure for this one?
I have similar problmes on a identical car
Polo 1.4 AUA 2001.

Customer complains of loss of power and dropping into limp mode. HE also thinks it runs ok with management light on but when the epc light comes on as well thats when it runs a lot worse!

Vehicle has been to a couple of different garages and had new map sensor and throttle body. An additional earth has been added to the throttle body by someone too.

I have had ECU tested, have tested compression and cambelt, earths on bulkhead checked and cleaned.

With a snap on Modis car returns
17566 (p1158) Manifold pressure sensor, not a plausible signal, intermittent
17950 (p1542) Angle sensor throttle motor not a plausible signal, intermittent

Thanks