1999 Legacy B4 bogging down and missfire..HELP!!!??

Right so a while ago my B4 was running realy rough revs were up and down like crazy and no power. It was brought to a mechanic who has since changed the MAF, ICV and a sensor on top of the gearbox which all made a big improvement. But still has a miss and will bog down 2 or 3 seconds after hitting first turbo. It boggs down hard. Have to stop and turn off the car and restart it and rev it to get it back to normal. Going pulling the plugs on her today to check plugs and spacing but have any of ye any idea as to wat could be causing this because it is driving me mad.
The only code showing up on the computer now is for knock sensor but i think that is because she is noticing the miss in the engine

ANY IDEAS??????

Thats a sh*t one.

Could be as simple as a wire to ecu or sensor that's done.

Id check fuel pressure? So check the vacuum line to fuel reg/fuel pressure gauge (Fuel pump) I had a Walbro in Dec 2016 that couldn't hold high fuel volume, but it sounded fine and showed perfect fuel pressure when turned on.

Check the other vac lines. If any vac lines feed anything else like a boost gauge disconnect the boost gauge line. Sometimes boost sensor piping gets T for aftermarket boost gauges.

Then id disconnect the actuator arm from the turbo and see then how the car behaves with little to no boost.

you wont get a knock sensor code if its detecting knock, you car detects knock often, thats what its there for

you'll get a knock sensor code if there is a problem with the sensor and its giving wild/rouge values or giving none at all and it'll drive like death

change it for a second hand one thats not got a crack in the plastic moulding. 20 bones should get you one or go to ICP and get a new one

http://www.importcarparts.co.uk/par...=2875&var=47&dc=0&gen=&searchKey=&searchPart=

great time to be buying in sterling