Over the past few months every once and a while my 2000 Silverado 4x4 will feel as if I'm power breaking it when I try and leave a stop light. I've researched a little and have seemed to find that it is a problem with the torque converter. I'll have an increase in rpm's but no increase in speed. It doesnt happen often, just a handful of times in the past 4 or 5 months. Fluid level is fine and it doesnt seem to be burnt. Its been about 30,000 since I flushed and changed the transmission fluid thats in it. The truck has about 120,000 on it (mostly highway), any suggestions would be greatly appreciated.