help 2000 caddy tdi losing power

Hi all sorry I'm new here and someone may have had the same problem but I have a caddy tdi which when running right it goes very well but just recently it has got sluggish and seems the turbo is not cutting in but then if I turn off the engine sometimes it would go back to normal any ideas what the problem could be any help appreciated. Its a 1.9 tdi x reg

Since it "…would go back to normal…" when you turn it off and then back on, something is causing it to go into limp mode. Even if the MIL doesn't come on, there will be a code stored in the ECU. Have it scanned and report back.

In the meantime, start reading here: http://forums.tdiclub.com/showthread.php?t=179589

Good luck!

Thanks I'll have it plugged in and see what comes up.

"limp mode" is the perfect search term to use here... lots of great threads and discussion and some good step-by-steps.

Had my caddy plugged in and came up with fault code 4626 boost pressure control difference any ideas how to solve this problem???