Been having an issue with my 2000 Sable w/ 24 valve dual overhead cam engine:

It has a major miss/stutter/hesitation (not sure of the official name) right when I first start the car in the morning, then it goes away for a bit. Taking off from a stop it hesitates again. It was intermittent over the last couple of weeks but it's all the time now and occurs whenever I slow down and especially taking off from a stop. About a week ago I got stuck in stop-n-go freeway traffic. I was rather hot outside. At first car ran fine then after a while it began to miss real bad and I didn't think I would make it off the freeway. When it cooled down the miss went away.

I used an Innova 3100 Scanner on it and the there are no codes and my emission status is GREEN.

 

Has to be either fuel or spark. If you don't know how old the ignition bits are, they should be considered for replacement. Sometimes fuel pumps and coils act up intermittent. Fuel filter may need replaced as well. Good luck.
Gator