engine issues tempramentle

ok so i am guessing this is a sensor fault or a couple of them but theyr annoying so here goes car is a classic wrx import i have since changed the engine since mine had been abused. i changed it with an r reg uk spec engine that had the coil pack in the centre of the inlet and i swapped all my sensors/inlet over.

i let the car warm up to half way and if i was to give it beans the power is hesitant it will boost fine then power will feel strangled but the longer i drive it around the better it runs untill eventually it runs fine boosts fine but after a bit of zelous driveing it will sometimes cut out when pulling up to a junction. The last problem is it sometiems overboosts and the safety feature will kick in and it cuts the fuel off.

I have changed the maf but this is all I have changed anyone else have any ideas what these little niggles could be? any help appreciated.

What ecu is on the car now ? Does the Engine light coime on at all ? Any mods ?

havnt actually checked the ecu but im presuming its standard no other noticeable mods besides an air filter iv recently put a 3" decat on it but it ran tempramentle like this before that no engine management light wheres the ecu at on these?

Ecu on passanger footwell mate

what would i be looking for on the ecu?

If it is the first time you have driven it since the engine swap, you will of had battery unplugged for a while. This im told on my98 car resets ECU, it looses everything, mine used to stall at junctions, jerk about, run rough as toast. It only happened everytime i unplugged battery for a while (say over an hour). My neighbour told me (a mechanic) that the ECU has to learn your driving style again, throttle position etc. this maybe whats wrong with it mate. If so good 50mile trip will sort it out.