Volvo: CO2 output problem, mass air flow meter, mass air flow

Question
1989 (Swedish built) 760 GLE, Renault 2.8 Litre. Engine in excellent condition with 160k original miles. After full tune-up (new wires, plugs, etc) the co2 was still over 200 ppm (10 times standard) and I was wanting to change/repair the sender unit that was telling the injection system that it was starved for fuel, resulting in over-richness and 10 mpg. Please advise... THANK YOU.  

Answer
Paul,
The sender as you are calling it, should really be a Mass air flow meter. That part is in fact replaceable and is the piece that is in the hose that leads to the throttle housing. It has a wire harness that goes to it. Are you sure that the O2 sensor is operating and there are no intake manifold leaks?