I have a few questions about my 2014 Mitsubishi Outlander Sport ES. I bought it used, it only had 10,000 miles on it. It currently had 153K miles on it.

It has been running GREAT until recently. Now there are several noises that are new and I would like your professional opinion about what might be causing the noises. Additionally, the gas mileage has dropped tremendously in the past 3 months.

The 1st noise is coming from the CV transmission. (I think) When I am driving at highway speeds (65 mph to 75 mph) after about 40 minutes of continuous driving, when I try to pass another vehicle, I hear a whining noise. When I decelerate, the noise goes away. Recently on one of my trips to work, (after hearing this whining noise), the idiot light came on that read: "Transmission Overheating, Slow Down". I thought the fluid may have been low. That was not the case and there are no apparent leaks. I changed the CVT fluid with Mitsubishi's Outrageously priced CVT fluid at 55K and 100K miles. At 100K miles, I changed the CVT fluid and both filters. Then again recently at 150K miles. While driving slow (under 55 mph), I never hear that whining noise, only at highway speeds. Any suggestions?

Thanks