My. He y malibu 2008 works fine on cold weather but when temperature rise to the 90’s powere reduced mode starts to kick in. Does temperature affects the car? How can it be fixed?
Is there a reduced power mode, message? Check the tac/ throttle actuator control. A problem in that system can cause that message. I can ask the general questions, how long since a tune-up, any applicable trouble codes? Yes, temp can make a difference. Generally it runs a little richer on a cold engine. A hot engine, a little leaner. I'm sure others can give better explanation when it comes to temp. good luck