2000 Volvo S70 Automatic Transmission . 85,000 miles

Here is the problem:

-from a stop, when i step on the gas pedal it sometimes is hesitant when shifting like the gearing is off. If I am sitting in traffic, moving slow, and the transmission is both upshifting and downshifting, the shifting is not smooth. But if driving 65 or so on the freeway it shifts smoothly.

-when stopping at a red light for example, as the automatic trans downshifts from 3rd into 2nd, or 2nd into 1st, it stuggles to downshift correctly. Then, as i slow to a stop, the engine almost dies out, then revs back up. (i can feel it speed up as my foot is on the brake) .

Once, i was forced to stopped quickly because of a mattress in the road. I didn;t skid to a stop but had to stop pretty fast. When i did this, the car shut off. I had to put it into park, and restart it.

-And It seems like it may be idling a bit fast.

*****....HOWEVER, one thing I have noticed it that if I push down the "W" button for winter driving, none of this seems to be a problem. Could all of this be caused by a sensor, possibly a gear position sensor????

The tranny fluid is full.

I while back I was told that this might be the issue:

When they get dirty there is like a carbon build up which throws off the electronic settings. So when you let off the throttle it seals and cuts off all the air through the throttle body stalling the car.
Also when you slow down does the idle drop low then come back up?
If so that is the classic sign of a dirty throttle body.

Does the gear position sensor make sense???

 

I would clean the throttle body first. Also if the fluid is dirty replace it.