pwr loss

[toont]

I have a 2012 3.8 sedan that periodically will cut all engine pwr when slowing under 20mph or coming to a stop?

 

[landtuna]

More info needed.

Does the engine quit or just slow? If it slows, does it idle or die?

How are you driving before this happens (freeway speeds, city street speeds etc.).

Does it happen only with the A/C operating?

Do you have any warning lamps lit or engine check light on? If so what lamps are lit - what is the engine code?

What is the level of gas in the tank when this happens and does it happen after a fill-up?

 

[Rey]

At those low speeds you mention the transmission is downshifting to lower gear(s) and engine rpm is reduced to idle speed. It appears that your motor is having problems lowering to idle speed. Generally, idle speed control in fuel injected cars is separately managed from any other rpm range.
This can be "fixed" by your dealer.