aup..ive had my tubo 2000 re-mapped with a td05 turbo, full stainless with de-cat, fuel pump and front mount i/c, now then this might be wrong but hear me out when they mapped the car it was a nice warm day and the car was running 1.4bar on full chat and everything felt great however when the the outside temp dropped at night the boost climbed to 1.5bar thats when it started to misfire ever so slightly. since then when ever ive been out in the car the temp outside has been warm so only running 1.4bar with no misfire but as soon as i go out at night it comes back so does this mean they have set up the car to run fine on the boost it made on the day of the map and when im out in it on cold dense days (nights) its making more boost and the ecu dont know whats goin off???????? ive changed the plugs for good measure but still this problem is still hear. its my first subaru so dont shoot me down if im way off

 

On the newage ECU's there are compensatory tables for this situation, where the wastegate duty % will be decreased if IAT falls below a certain level, not sure about the classic ECU. Might be worth a quick chat with the mapper.

 

Were the Plug gaps checked?? if not give them a check and if bigger than 0.7mm bring them down to that .