2003 Ford Taurus Acceleration, Stuttering

Hi,
This is a bit of a long story so bear with me. I have a 2003 Ford Taurus 3.0L v6 Overhead Valve with 120,000 miles. 2 months ago my airbag light started flashing a code. The code was 42. I looked online and found the code meant there was a problem with the O2 sensors. I went to Advance Auto and bought 4 new Bosch O2 sensors. The Motocraft O2 sensors that were in the car were 2 different colors, Blue and Green, 2 of each color. One color was a few inches shorter than the other. The Bosch sensors had no difference between each other except part numbers. Now I probably should have stopped here and consulted a pro but for whatever reason I didn't and proceeded to replace the sensors anyway. It was only later on that I realized that the car has 2 upstream and 2 downstream sensors. After the replacement of the sensors, my car was running fine but the airbag light was still on. It ran fine like this up until 2 weeks ago. After turning on my car and running it for awhile (30 min +) when I pushed on the gas pedal the car would lose acceleration power, start stuttering and hesitate when pushing the gas, bog down, and eventually all the lights on the dash would be lit and the engine would shut off (I would not lose electrical power because my lights and radio were still on). After the engine would shut off, I would turn off the car and then turn it back on again and it would run fine for a few miles but the check engine light would remain lit and then it would shut off again. This would continue until I reched my destination. Later I realized it seemed to happen when the car ran for a little while and I went up a hill or two. So, I figured lets check the fuel filter. I took it off and blew through it and it looked dirty so I replaced it. The car still acted up and shut off. I took it to the garage and they said the check engine light code read a misfire in cylinder 6 and they mentioned another code that meant it was either the spark plugs or the fuel pump. So they replaced the plugs and the wire set and tried it, it still shut off. We then replaced the fuel pump and then tried it. The car no longer shut off. BUT still stuttered and hesitated when pushing the gas, had a lose of acceleration power, and gets bogged down. I then looked online again and found it could be the TPS (throttle positioning sensor) or Mass airflow sensor. The MAS is $213 to replace and the TPs is $25. So I replaced the TPS. I am still having the same issues. So, after replacing the fuel filter, spark plugs, wire set, fuel pump, and Throttle Positioning Sensor, I figured enough is enough and I would ask you guys what you think. Could it be the MAS, or could it be the O2 sensors since I really didn't know what the heck I was doin with them and my airbag light is still flashing a code 42 or could it be something else?
UPDATE: I tried putting fuel injector cleaner in with the gas, no effect. I took off my Mass Airflow Sensor and cleaned it with an electronic parts cleaner. I seem to have little more power now but the car is still having acceleration issues and stuttering when pushing on the gas. Should I replace the MAS? Also I have been told that my airbag light code would have nothing to do with O2 sensors. Is this correct?
UPDATE2: I replaced the Mass Airflow Sensor and cleaned throttle body. Things are a little better but not resolved. Still have a lack of power (takes more to make the car accelerate). Car seems to stutter and get bogged down still. I am also now noticing that once the car reaches normal operating temp and come to a stop, I can smell gas(exhaust). Please Help