Automatic Transmission problems of the 2007 Hyundai Entourage

The Entourage began running like it was not getting fuel, jerking, hesitating, etc. Took to dealer they said the oil was the issue. Oil change and flush. 1 week later began with issues again, dealer refused to look at it. Went to outside mechanic said misfire code was bad coil. Changed, 1 week late symptoms recurred. Hyundai dealer still refused to look stating it was an oil issue. Went back to same mechanic diagnosed same misfire code and then said a second came up and was the pmc was corrupted.

My Entourage exhibits intermittent significant low-speed engine braking when driving in the auto 'drive' position. This braking effect is similar in effect to the actual light application of the brakes. This was immediately reported to the Hyundai dealer upon purchase delivery of the vehicle. Dealer has attempted to fix by performing transmission re-programming. This has modified the behavior to make the occurrence of this much more intermittent, but still not fixed it. I have two safety concerns with this. The first is I have almost been rear-ended by another driver once, and that was on dry pavement. This vehicle actually performs a braking function without the benefit of the vehicles brake lights being displayed. We live in wisconsin where the road conditions get icy during the winter. The braking is significant enough that I'm concerned about it causing the vehicle to enter an uncontrolled skid on icy roads, particularly in conditions of approaching intersections requiring a stop or yield and also when exiting highway ramps which can become very slippery. Hyundai and dealer have both now decided this is 'normal', even though it is very intermittent. Hyundai will no longer address this. The vehicle operates to coast in a safe manner about half the time the gas pedal is released, which leads me to believe it should be capable of doing so all the time. This appears to be a design flaw with the engine/powertrain that can be affected by programming, but Hyundai will no longer address and has left me with no recourse for resolving as they will not recognize this as a valid problem. The engine/transmission modules do not display any problem codes for this, so Hyundai's stance is it is not a problem.