Volvo: Volvo 240 dl 1988 Stalls, volvo 240 dl, fuel mixture

Question
Car will idle with AMM disconnected and also runs well at higher speed in that mode.  A little rough at low speeds.  If AMM plugged in the car dies immediately. Ohms readings between the six terminals are:
    1     2     3     4     5     6
1          0     2.8   18k   19k   527
2                2.9   18.7k 19.1k 527
3                      18.5k 19k   530
4                            38k   19k
5                                  19k

There is also a screw hidden under a protective cap just beside the electrical plug.  What does that do???

Is there a schematic or an explanation of what the air mass meter does and symptoms/

Thanks and keep smiling

Answer
Lys,
Replace the MAF that should fix it. That is an adjusting screw to fine turn the fuel mixture.
Other fourms might have a form of symtoms, however I do not know any.
Common you have the MAF plugged in and it runs poorly unplug it and the it runs better, but not great. Sign of MAF gone bad.