300D startup problems

Dear NG.
I have a 91 w124 300D with 220 K on the clock, which have served me well since maj 2004. Of course there have been minor problems, but thanks to
mbz.org and this NG, i have been able to solve them my self.
But now it acts strange every time i start it up. It seems as if the "idlespeed" only is about 400 rpm, the antibrake warninglight is on and the "RPM-meter" dos not work. The car kan be driven, but it feels as if there is less power than normal.
After about a minute, the antibrake warninglight goes out, the RPM-meter starts working again, and the car drives normal again.
It makes no difference if the motor is cold or warm when i start it. It reacts the same way as described above.
Any ideas of what could be the problem.
Mikael Christiansen
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