Sudden power loss on 2006 Kia Sorento

The problem is a sudden loss of power while driving. It has happened while driving in the fast lane on the interstate with lots of traffic as well as on residential streets. The engine seems to be running well, but there is no response from the transmission. Coasting to the side of the road and stopping completely is the only alternative. After turning off the engine and starting it up again it may run fine or it may do it again. We have had it to the dealer once and the mechanic said there was nothing wrong.

Asked by for the 2006 Kia Sorento
No answer but feel your pain. Have two Buicks '98 & '04 (Regal, 3.8 L) that have done this. Took them to the dealer, no error codes so they kept it and let it run with the diagnostic machine attached, ran it for 7 (!) hours and nothing happened. When the mechanic took it around the corner to get gas, it died enroute. Extremely frustrating. Once the car restarts (which it does either by itself or with the ignition) the code resets and the mechanics don't know what happened. The likely cause I was told is a flaw in the primary computer module, replacement $2500. My solution, trade-in,no more Buicks.
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This happened to me several times ,problem was rectified after a tip on internet suggesting it was the diesel filter becoming glogged due to wax forming during cold weather. When I changed the fuel filter I had a big increase in power and a solved problem I have a 2005 Sorento, great car!