A friend of mine has an S-10 that will just rev up at a stop light, and then hit hard and go, but not all the time. It's a 2000 with a 4 banger, and I assume it's a 4l60e, it is an automatic. So I ask, is it on a hill, flat ground etc... She said it did not matter. But after it goes everything works fine, shifts good no slipping, just goes fine. Does not happen all the time, just now and then. They tell me fluid is full, and it has 47K original miles. Any ideas????
Thanks,

Mark

 

Over fill it buy a quart or two and see if that changes. I have seen the short filters on deep pan's or loose filters in the filter seal give this problem. I have also had input shaft sealing rings shrink and cause the forward clutch to not apply until line pressure rises and makes a good seal.
2000 with 47k miles hasn't been driven a lot, it could have tulip-ed a lip seal too.
It would be nice to see what pressure it has under the fault.

 

47,000 miles. Sounds like it didn't get driven and has sat for long periods possibly. My guess would be an internal fluid circuit leaking. Does it occur more when the vehicle is not to operating temp?