I have a 93 lgacy rs and every time the boost comes on the car shakes and surges, sometimes violently. both the engines power delivery and boost seem to jump around however the car is so jumpy many times the boost gauge cannot react fast enough to show much change. I have tried to fix it by:
replacing the bov with a turbosmart recirculating type.
substituting a manual boost controller for the stock electronic one(now stock again).
replaced hoses and checked endlessly for vacuum leaks.
I did find one very large vacuum leak (pre-turbo) but fixing this did virtually nothing. I also unplugged the battery to try to reset the ecu still nothing.
Has anyone heard of anything like this? does anyone have any suggestions?