imprezapeej

Hi all, just wondered if any of you could help me....I have a Classic Scooby that i took on which needed a lot of work. The car has no history what so ever and i am trying to decipher what exactly it is and where it's from. So it had a TD05 on it, but i have put a TD04 on it now(this is the first odd bit: when i first had the car the turbo was seized and yet since removing it it has freed up completely..??!!) anyway the td04 is on but i am struggling to see proper performance as i'm getting flat spots through the rev range range (as if it's slipping similar to as a clutch would) usually 3rd,4th & 5th gear, almost as if when you boot it, the turbo has to try and catch up...!! So i took the passenger footwell back to have a look at the ECU and it's an E3 is this the right one...??is it likely a UK car or an import...??......Any help much appreciated. I am very keen to get her running 100% again but this is very frustrating.....I have thought that perhaps the car was mapped for the TD05 that was on it and that now i have replaced it with the TD04 that it is simply not coping and perhaps in need of a remap....??? Anyway thanks in advance.