I am assuming that you got this fixed already. I had a similar problem where the car would stall when i come to a stop at red light. The fix for me was to properly clean inside the throttle body. On my 2010 fusion 3.0 v6, the throttle controls the idle. If there is dirt or smog build up, it could prevent the vehicle from breathing properly and can cause the car to stall.

 

No I actually don't have this fixed yet. And I just replaced the TB just a few months ago why would it be causing me problems already?

 

There could be tons of reasons. Your symptoms fall in line with mines. After i clean the throttle. The car no longer stalls at idle. However, at times when decelerating and accelerating, i felt a slight stumble (felt like an engine misfire).
Replacing the air filter took care of that issue. (side note, i moved into a new DUSTY as hell area. Only took 3 weeks of moving here for me to have these stalling at idle issues and clogged up air filter/dirty throttle.)

Even if your throttle body is new, dirt build up or clogged up air filter is not a throttle body issue. The one peace of evidence that you want to focus on is that your symptoms happen at idle. The throttle body on our fusions control the idle. When idling the throttle closes and leaves a small air gap. Therefore dirt deposits near and around the throttle plate would have its biggest noticeable impact when at idle. If the engine is not getting enough air/oxygen at idle through the throttle body, the engine can stumble/hesitate/stall. Also a good idea to inspect and possibly replace the air filter like i did.

Good luck.

 

Have you checked for any vacuum leaks?

 

Yea I was about to say that it sounds more like a vac. leak

 

If you have the torque pro android application (or some scan tool) then it can QUICKLY help you determine whether it is a vacuum leak or what i suspect to be a dirty Throttle body.

Monitoring the PIDs for short term and long term fuel trim will tell give you the proper direction. Again, i had same issue. Car stalled everytime at the stop light on my way home from work. Pulled over to the side of the road, pulled out my android phone with the torque app and quickly diagnosed (in my case) that i had no vacuum leak (fuel trims were normal). However, when i start the car it would run for about 5 seconds then die if i did not depressed the throttle. So i start the car, and monitor the fuel trims. The first 4 seconds showed normal fuel trim readings but when the car was about to die, the short term fuel trims quickly went to high negatives (around -21) then die. My interpretation of this at the time was because the car was being starved of oxygen at the time and the fuel/air mixture became rich ,i.e not enough air, the engine computer signal the injectors to take away fuel and thus cause the engine to stall and the negative fuel trims. This here lead me to investigate the throttle and clean it with whatever i had in the car at the time and got me back on the road.

Hope my efforts may help.