Volvo Repair: Air mass meter, mass air flow, gas additive

Question
I have a 1994 Volvo 850 and have been in non-operative since 2002 due to my job overseas.  Last month when I came back and jump started the car, the engine have been running very rough since then.  The check engine light did came up and showed air mass meter, but after I reset the check engine light, it never came back again, but the car still running very rough.  It is especially rough when accelerating from 0 to 30 miles, and runs ok on high way speed.  I have added some gas additive to see if it run better, but seems the same.  I checked the price for air mass meter and it runs very expansive.  Is this the problem?

Answer
i dont thing you need new mass air flow but it is posible
you can unplug it when the car runs see if it runs better than if not due tune uo with new wires cap rotor plugs  dont put any gas adative  it better if you can drain the fuel from tank that can be also problem if the car sits to long fuel goes bad    
try that first