Weird Idle problem.

[flaatr@yahoo.com (Euroroc II)]

Heres one for ya...

My car idles perfectly, closed loop @ 870 RPM, smooth, stock cam. new 
distributor & Cap & Rotor, differential pressure regulator & fuel 
accumulator are new too along with plugs, filter, and oil. The alternator 
is working fine and the battery is happy, 13.5-14V from alternator, no hard 
cranking when starting,  etc. etc. etc.

When I drive the car and come to a stop, slowing in gear to below 2K before 
letting the clutch out the engine speed will drop to 500 RPM'ish bog for a 
split second then return to perfect idle (or lower and occasionally stalls 
although not that often) . This is repeatable and annoying. Revving up and 
letting it drop is fine, holding at a higher RPM and letting it drop is 
fine. the problem only seems to happen when the car is driven, higher RPM 
under load and let it out of gear under 2K. Letting it out of gear above 2K 
is good, engine returns to idle without dipping.

Strange thing is that if I have the A/C on the entire problem goes away.

I've had it in the shop several times, for many days, and they can't seem 
to figure it out. The problem remains so I ask the group...

Anyone have this problem before and how did you fix it? I may have left out 
a detail or two so ask me any questions you have.

-Raffi