Jetta transmission problem

I have a 95 jetta, V6, GLS. Engine was blown about 2 years ago. Have about 35,000 on new rebuilt engine. Latest problem: Step on the gas but go nowhere. Engine sounds great, reves as I step on gas but still no motion. I get going about 25 mph, it shifts into 2nd, still not much jice then finally after it goes into 3rd it catches in and off I go with full power and motion. Very upsetting to me because I had all the switches replaces about a year ago. It seems with this car, it's always one thing or another. It is sitting at the garage until Monday when they go into the problem. Any guidance would be appreciated.
Thanks, Brent

Is this auto or manual? Manual = clutch is worn out. If auto have you checked the ATF level? What switches?