Dima.....turning that 3mm allen screw 1/4 turn is a lot of adjustment...if the setting has never been reset, some profile wear on the screw tip will over adjust the setting when you move it 1/4 turn......do you remember where it was ?
If so, go back to that and bump it up about 1/10 th of a turn and drive it to see if problem resolved.....if not do it again until you are less then 1/4 turn up.
The Califonian emission levels for those cars was very lean and coupled with the vacuum retard it promoted what you where experiencing.
The vacuum retard was to do two things...
#1...Reduce tail pipe c/o reading.
#2...Cause the idle to recover when the rpm's dropped because the vacuum would decay and this would advance the timing by what ever the vacuum pulled off.......however, unless the fuel/spark/compressions/vacuum valves/system is top notch, it would stall.
but who cared as long as it passed CARB test.
Unless you have a 'dual/twin action vacuum canister' with two seperate vacuum hose connections, this information is redundant...I have usually seen these 'twin acting vac' canisters' on 6 cylinder engines...some engines had a single acting vacuum canister that was only retard, unlike usual function of advance.
Emission routings pages for your 107/116 :
http://putfile.com/pic.php?pic=4/11508253949.jpg&s=x402
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http://putfile.com/pic.php?pic=4/11508201123.jpg&s=x402
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