Volvo: runs rough-no power, mass air flow meter, mass air flow sensor

Question
I have an 84 240 DL that has been experiencing periodic power eductions under load, idles rough, stalls ocassionally when you stop at a light and has an ocassional backfire.  This morning it did the same but then quickly lost power and now wont throttle up at all, it just idles rough.  Your thoughts would be appreciated.

Thanks, John  

Answer
John,
Fuel pressure could be low, not getting enough gas, large vacuum leak causing lean fuel mixture, Mass air flow sensor that is not correcting the air fuel mixture in the cylinders. Try unplugging the Mass air flow meter when it is running poorly and see if it then runs better. That would be a sign the MAF is bad. It will run with the MAF unplugged but the acceleration will be sluggish.
The in tank pump maybe inop and not suppling fuel to the main pump and you are not getting enough fuel.