Check the wastegate to make sure it's operating smoothly and properly. My 98 was doing the exact same thing and swapping the transducers did not resolve or move the problem to the EGR system like would happen if the transducer was the culprit. I ended up swapping the wastegate actuator from my spare parts turbo and lubed up the pivot point and have not had the issue return.

Disconnect the actuator on the turbo and see if the arm moves smoothly. If so it is probably just the actuator which you can test with a mity vac. If the actuator operates fine and holds vacuum then the pivot might be binding up, could happen from soot build up.

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'98 E300 Turbo "Juliette"
'85 Federal 300TD