idle problem

[m.s at biosys.net]

I have a 92 sr20de that idles poorly if at all. If  i drop the rpm
slowly it will idle. If i just push in the clutch it dies. It seems
as if the ecu tries to catch it as the rpms drop and the tach needle
bounces slowly up and down until it either stabilizes or stalls which
leads me to suspect an air circuit problem. I have cleaned the
throttle body several times, replaced plugs and tuned the engine. It
works ok for a while and gradually the problem comes back. After
putting up with this for 18 months i finally broke down and put it on
a diagnostic machine at the dealer. The service manager said that the
AAC valve needs to be replaced. My questions are:

1. Is this likely the cause?
2. Can this valve be cleaned instead of repaired?

thanks
michael