The same thing happened to me after getting a Revo map,ran great for 2 days then total loss of power when on boost.first i thought it was the forge D.V but it was ok,then i booked into VW and they said it had a bad misfire on piston 2 so they changed no.2 injector and the fault was still there.After a week at the dealers it ended up being the ecu which was replaced under warranty.
....Have you gone back to a Revo remap?
Sounds as if you were lucky getting a new ECU under warranty when you had remapped the original one! 
Did the Revo tuner you used, firstly check your car for status/faults, then use a rolling-road and also finally drive it with a laptop attached?
RR, yes i was lucky to get a new ecu, but they could'nt prove the car had been mapped and i was'nt going to tell them.Also the Revo tuner checked the car for faults and it showed a fault on no.2 piston (misfire) and advised me to take it back to the dealer,anyway went back to the Revo tuner and told them the map damaged the ecu and they said the revo would'nt have damaged it and would i like them to put the map back on, this was'nt going to happen and asked for the money back because i am not paying £900 for a new ecu if it goes wrong again.
