Peugeot 205 gti 1.6 (90') idle and stalling problem

Hi everyone!

I recently bought an 205 gti and it has a big problem.

The car is a rocket btw , great power , engine starts with no
problems, but the car is having a problem
with idling and stalling.

Description:
When i start the car it goes great before it drops the rpm from 1500 to
1100 (worm up time). The idle speed on my car hunts from 1100 to 500 or
600 rpm and stalls when i stop the car or not pushing the throttle. It
gets worse when i put on lights or any electrical thing. Funny thing is
that the battery is full
, no light intensity changing when hunts rpm. I did this : changed oil
and filter (10-40 oil), air filter , fuel
injection totally cleaned , opened the air sensor and cleaned out the
graphite track with alcohol (there
was two lines from needle that left on the track) cleaned cylinder
where the oil is filling , metal net ball
(or something) in the cap. No results.
I saw one screw that is worn out (from a lot of adjustments i think.)
on throttle body(not adjustable). I even adjusted the idle speed with
air bypass screw on air flow sensor and some gold colored big screw on
throttle body . Also adjusted the bosch switch parallel to throttle to
click when throttle changes (tested with ohm meter ok.)

Any help will be great. Thanks.