Help! Impreza Boost problems + running lumpy
 

As above really, anyone got any ideas? My car is a 2000W reg impreza turbo and it runs lumpy on idle (as though its hunting) and as you go through the gears it jerks and misses slightly as the revs rise, whether your driving slow or not. Also when you do give it some:) it sometimes cuts the boost to 0.4/0.5 bar and won't go any higher, if you turn the car off and restart it it'll let you have full boost again (1 bar). Also if you disconnect the pipe that goes from the actuator to the boost solenoid it just overboosts (1.1-1.2).

I've had it on the old diagnostics machine at subaru, and to start with it gave a MAF fault so he changed the MAF sensor and then it wouldn't boost at all..:wonder: so he put the old one back on.
Today he changed the oxygen sensor (to cure the lumpiness) and the boost solenoid. It now runs ok for about 30secs on idle then back to lumpiness and it cuts the boost more often now!!:brickwall
Any ideas anyone?? please!!??