I just pulled mine tonight and realized that it's not that dirty AND it was loose on the block. So the gasket was leaking.

I would say pull it and clean/inspect it first. Check to see if it holds a vacuum. You can see the diaphragm if you hold it upside down. Mine has 129k on it and it wasn't restricted at all. Some carbon build up but nothing some carburetor cleaner couldn't take care of.

'86 Toyo 4wd
'04 600RR