Re: Lumpy Idle on 164 V6 24v
The idle air bypass valve is on the back of the plenum, in front of the false bulkhead. It's cylindrical, about 75 mm long and lies horizontally. They do go wrong and can leak air at the grommet into the plenum. Disconnect it and spray inside with carb cleaner. I sprayed some WD40 into it after cleaning as well.
Other things to look at: all the hoses to the plenum, bottom of the corrugated hose from AFM to throttle body, clean throttle body with carb cleaner, clean AFM with carb cleaner.
Badgers Nadgers had a rough idle on his Super but I can't remember what the cause was. Have a search for his posts - it wasn't long ago that he posted that the problem was solved. BN's car is a late model with the more complex exhaust valve, bigger oil separator pipe and so on.
The can be a bugger to sort out. Hope it all goes well.