I checked the vacuum on my MPS today and I think it's not working properly and making the motor run rich.. I pumped 20 in/hg and it went:
down to 15 in/hg in 16 seconds,
down to 10 in/hg by 50 seconds
down to 5 in/hg by 2 minutes. Sounds kaput? Anyone have a good one I could buy? It's for a '72 1.7L, the part # on mine is 022 906 051E. Anyone know if other car models use the same one like a VW?

Your MPS should not drop below 15" HG in 5 minutes. It is getting hard to find a good used one, but they are out there. I would try taking it apart (without disturbing the adjustment screw). If your diaphragm is cracked, you are screwed. Otherwise, try to re-seal it with some Permatex on the seals.

If you can't find a good used one, Parts Heaven will rebuild yours for about $165. partshvn@ix.netcom.com

I am not sure if MPS's from other cars will work.

Good luck!

You need a Bosch 0 280 100 049 or 0 280 100 050.

Other than the '72 - '73 Porsche 914, it was fitted to the Volkswagen 412 1.7.

I have one if you need it (049). It has the following characteristics:

Leakdown from 20" ...

5" in 2 minutes
5.5" in 3 minutes
6" in 4 minutes
7" in 5 minutes
7.5" in 6 minutes

98 ohms between terminals 7 & 15
350 ohms between terminals 8 & 10
None of the terminals short to ground
Epoxy plug is in place and has not been disturbed.

If interested, shoot me a PM