Engine racing on park (2000 Montana)

This started about 5 months ago... When the van is stopped and put in park, the engine is heard racing up, and the RPM needle runs upwards. A couple of dealers I talked to have never heard of this before.

This happens maybe 2 or 3 times each month. The van has about 32,000 miles on it.

Before putting the van in park I have also felt a vibration on the brake pedal when the van is in drive. When this vibration is felt I know that the engine will race in park. Otherwise there is no vibration.

After the ignition is turned off, and on again, everything is fine.

Thanks,
Upkar

what about the temp? Does it go up too? When my intake manifold was going my van reved high in park and the temp shot up becaus eof the leaky coolant.

I don't recall seeing the temp go up. Since I posted the original message the dealer has replaced the manifold gasket and bolts. I guess I will have to wait and see if it happens again! Thanks.