Buy a 240D, no Turbo lag, instant power to the rear wheels when the clutch is released.

Problem solved.
The intertaining part is, the DB that was behind me trying to launch his V8 Rocket into my trunk, is now ahead of me at the next red light. I roll in behind him as the light turns green, and off they go again, and I just keep rolling along w/o stopping.
These old Diesels are not fast off the line, but are long lived and dependable.
X2 on cleaning out your boost line from the intake manifold to the switch over valve and on to the ALDA. there could be a problem with the S/O valve, and it is leaking the boost.
Charlie