Transmission problems and slight whining?

I have a 1995 Mitsubishi 3000GT, automatic trans. I got the transmission flushed about 1,500 miles ago, it has 99,940 on it right now. Today it started doing something i have never had a problem with before. I went to stop at a stop at a red light and as soon as it shifter down to 2nd or 1st gear it felt like the brakes were put on, hard. It did it no more than maybe a second if that, then let up. When i went to go at the green light, the car went and then the engine reved up to 4K rpm, but wasnt moving the car. I let off the gas and pressed on it again, it finally went. 2nd red light, exact same thing happens. I bring it home and park it for about 6 hours or so and try to run it again after it cooled. It was fine for the first 13 miles and then it started it again, not as bad this time though. I turned overdrive off and it helped a little, but now there is a slight whine. Repairable or do i need a completely new trans? Worth it? I love the car.