Volvo Repair: 96 850 Hesitation, mass air flow, loose hose

Question
I just want to thank you ahead of time, Roger. I have a 96 850 sedan and it has been continually losing power and sputtering for a matter of weeks now. My mechanic has put in two mass air flow boxes and seems to be quite stumped. The first time it was a bad fuel filter, then a loose hose, now he doesn't know. The car has be driven for around 30 minutes for it to start acting up, but when it does, it's quite frustrating, seeing as how the car's power is basically gone. The accelerator has to be floored for any power to go the car when acting up, and it violently vibrates when slowing down as well. Any, and I really mean any solution or cause would be greatly welcomed. Thanks again,
                             -Michael

Answer
Michael, I've never seen a volvo Fuel filter go bad, especially on an 850.  The 850 is prone to having fuel pump issues and this is what it sounds to me by your description.   I would have a fuel pressure tester hooked up to the car so he can see if there is any drop in pressure.  If not, then its possible that its ignition related.  Hope this helped.  Roger