I have a 2000 New Beetle with 105,000 miles on it and today all of a sudden as I was slowing down for a traffic light, it hard shifted down and when I sped up again it didn't want to go into 4th gear. I then stopped at another light and it did the same thing but acted like it didn't want to go into 3rd gear after accelerating. After the engine and transmission cooled down it ran fine for about 5 miles but started again. What could this be? Is it low on fluid?