I have a 2005 Highlander and I have to downshift the Automatic into 3rd before I make a left or right hand turn then accelerate and up-shift or else the vehicle hits a flat spot with little acceleration.
The Mech told me to do that because thats how the Highlanders were made to save on gas. Sounds far fetched to me, but ? ? ?
The fuel supply, to the engine, is suspect. Change the fuel filter, and have a mechanic do a fuel pressure check with the engine under load.
Sounds totally far fetched to me also Falcon. Just as hellokit suggests, it sounds like a fuel related issued. If it was an older car with a carb, it would simply indicate a low or high fuel float setting. But with fuel under pressure now on the multiport systems, it has to be related to the fuel inside the tank or filter, or screen assembly. Does it do this even when the tank is full? If so, then something is loose or moving around during the turn. I’d first start with a thorough inspection of everything under the hood and the car for security.