Was driving down the road today, put my foot down hard; then all of a sudden the vehicle jerked and stalled (travelling ~70-80km/h).
Now the vehicle runs fine, up until 4krpm and then it starts to stall, create a bashing sound and jerks. You can ease the accelerator up really slowly and make the car speed up gradually.
When idling the revs are constantly increasing/decreasing. The air sensor has been cleaned and the air filter has been cleaned/oiled, I did them both today when the problem occurred.
The turbo appears to be working fine, the boost gauge is reading and you can hear the turbo winding up (until 4krpm).
I read that the green m/f adapter under the dash could be connected and create a restriction. I've had a look but all I can find is a green f-adapter which isn't connected to anything.
1999 Subaru Impreza WRX STi