The EGR delete will CAUSE this problem! Do not do it!

Check the obvious...mine was doing the same thing for the last week. I finally got in and checked the EGR vacuum hose. It had failed and was preventing the vacuum signal from getting to the EGR valve. No EGR valve actuation -> not pressure change in the intake -> computer sees a fault and turns off the turbocharger until you get above 3,000 - 3,200 RPM.

The reason it runs fine cold is that the emission programming will not try to actuate the EGR valve until the engine has warmed up -> it does not see the EGR valve problem.

Make sure you are getting a good vacuum signal to the EGR valve.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.