Hunting when you back off throttle

[VPCalais38]

I have a problem with my V6 VP Calais.

When I back off the throttle while driving the car hunts/surges. The tacho bounces up and down a couple of hundred rpm and if I am going slow it makes my diff clunk (car has done 320,000 so diff/uni's are buggered) because it is bouncing up and down in revs.

I have recently removed and cleaned out the Throttle Body and the IAC valve but this didnt help the hunting issue, in fact it just made the revs bounce faster.
I have been told this could be cused by the IAC valve being set incorrectly (28mm if I remember correctly) or have also been told the o2 sensor may be faulty.

Anyone had a similar problem with the V6's?

Gotta get this fixed before I take the old girl over the pits.

Cheers

[smokey_dj]

could also be a kick down cable issue as i found with mine

[xcop5l]

get another iac valve and put it on the old one is probably full of junk in the steeper motor