Does my 944s need a o2 sensor
 

IT DOESN'T START AT ALL BELOW 40 F, 40 TO 45 IT STARTS HARD AND IT HAS TO BE ABOVE 50F BEFORE IT STARTS WELL.EVEN WHEN IT'S FULLY WARMED UP IT SEEMS TO BE RUNNING A LITTLE RICH AND IT ONLY GET ABOUT 22MPG,I'VE HEARD THESE SHOULD ABOUT 30MPG IF YOU CAN DRIVE REASONABLY SLOW. I'LL ADMIT THATS PROBABLY AT LEAST PART OF MY MPG PROBLEM.ANY THOUGHTS GREATLY APPRECIATED. THANKS WALT:confused:

The o2 sensor has nothing to do with it starting. It actually only functions after the car warms up.

I would check for a massive vacuum leak somewhere, or a rip/hole in the J boot. These would cause the no-start issue, and poor mileage.

After you get it starting properly, then check the O2 sensor. It can clobber fuel mileage but like the previous poster said, it has no effect on starting.