My 850 seems to have lost its turbo boost. I can hear the turbo spool up primarily when the car is cold. It goes just into the white and then retards back down into the black. The turbo sounds fine, no grumbling or grinding. It was working fine, I replaced the vaccum lines running off the turbo boost regulator mounted on the airbox, and the turbo boost stoped working. All the lines are in the right place. Also, around 2.5K-3.5K the engine seems to have a lot of grumble to it, as well as at idle. Is the 850 engine just grumbly, or is this a problem? The check engine light is on, but no codes about the turbo problem, just misfiring in cylinder 1 and 3. I replaced plugs and cap and rotor, as they were fried. The light won't go out, even after trying to reset the codes. Could the turbo/harsh running be a computer failure somewhere, sensor?? Thanks a million for the help.

Brett