My car has a mileage of 16,000 miles and a CVT transmission. The transmission has been making problems lately. If the throttle is put down at half and helt that way, the RPMs would start fluctuating erratically. Normally, when you apply the gas pedal, there would be engine revving and shifting down. But, this transmission is unpredictable. Sometimes there would be a bit of revving and then the RPMs would decrease in higher gears. What should I do?