All,

2.1 '87 westy with AC, manual

I'm experiencing a slight pulsing vibration at idle. As soon as I get off
idle it goes away and the engine is smooth as can be. The pulsing does not
appear to be related to rpm fluctuations as the rpms seem to be holding
perfectly constant at around 825. The pulsing seems to occur about twice a
second. I can feel the pulsing through the seat and also the vibrations
when it pulses are enough to make things in the cabinets buzz, so I can
hear it. However, from the outside the engine sounds steady as can be.

Just looking for any ideas as to what this could be to help with my trouble
shooting. These are the relevant things that I have recently replaced with
no effect:

idle control valve
idle control module
throttle body
throttle switch
vacuum lines/hoses
checked for intake leaks, none
motor mounts
transmission mount
02 sensor
temp 2 sensor
all three belts

Thanks