1996 Volkswagen Golf Hesitation and stalling

I am kind of new to DIY(do it youeself) car maintenance so i will need evry help that i can i get.
i own a golf III '96 model about (169819KM).
i just bought this car about 4 months ago and i keep experiencing a loss of power whenever
i am about to overtake another car or when i stop (after a long time on the road) to maybe
get something.On starting the car it just would not respond immediately (it tends to stall,hesitate before finally picking up speed).

funny enough when i start the car in the morning it stays on 10 rpm for like five minuites
then it begins to drop to 9rpm,the next i notice is that it begins to oscillate
between 8 and 9 rpm(without touching the accelerator),it will then normalise for some time.this goess on untill i turn it off.

i have since changed the fuel pump(3 times) and the fuel filter.there was this "T" hose
that was torn and i had to change it with a modified one since i could not get the actual one.(See c ON FIG 1).
After the change of the hose there was some improvement as the loss of power situation occured less frequently.

A friend (who owns a similar car but diffrent fuel supply system from mine) now suggested that i check the air flow meter.Before taking the car to the automech shop i wanted to ask a few questions.

1.what kind of fuel supply system do i have (From Fig 1,2&3)?
2.what kind of engine do i have in the car?
3.What is the name of the device (see A in fig 1) and what does it do?
4.where is the Airflow meter located in the engine[is it B (in fig 2)]?
5.what can i do to stop the loss of power...since the use of a scanner is
out of the question...i say out of the question because where i am
nobody seems to know what to do and i have never heard of anybody
having it or knowing how to use it either.

I am really ready to get my hands dirty to get things right i just dont know what to do.
Thanks for your effort.