I have a 94 850 Turbo Sedan with 75K that does the same thing. According to the owners manual the valves are self adjusting and a tapping noise will be heard for the first few minutes until they adjust. I states not to go above 3000 RPMs until the engine has come to full temp. Also states that it can take up to 15 minutes for the adjustment period for cars that have been sitting for a long time (in storage?).

Also - for the Turbo models. 1) DO NOT REV THE ENGINE during the first minute or so until the turbo can get lubricated. 2) Do not rev the engine before shutting the engine off, and allow the car to idle after driving it hard. This allows time for the turbo to wind down and cool off.

This is all in the Owners manual, and in the service or warranty book under Turbo. Its not real obvious unless you read through it (it should be on page 1!)

What I do is start the car up, then put my stuff in the car, check tire pressure, or something to take a minute or so and drive it slower for the first mile or so. Coming home I just drive a bit slower when approaching the neighborhood to let it cool down. Better safe than having to replace a turbo unit or messing up the valve clearance...

Hope this helps

Joe - Orlando FL - 94 850 Turbo