i recently purchased a 97 4x4 auto. truck has 130k on it. shortly after buying the truck i noticed sometimes when i tried to take off, the rpms would raise up but the truck wouldnt move for a few seconds, then would catch hard and go. it is an intermittant problem that mostly happens from a dead stop. i have noticed it do it a couple of times going down the interstate if someone cut me off and i had to brake hard to avoid hitting them, it would slip for a second before catching again. all shifts feel nice and firm like they should, it does not slip between gear changes. fluid is full and clean looking, anyone got a suggestions?

 

I would check vacum lines mine is doing somthing similar.My brother has the same truck as mine and found a vacum leak witch fixed his.HOPE IT WORKS GOOD LUCK.