06 grand prix transmition issue

[BlenkerGXP]

i am having a issue when i shift the car into drive and start to get on the throttle it slams into gear as if it were low on trans fluid but its full can any on help me out it only happens in first gear and when taking off at a stop light it was low and i filled it and it does not do it as much but some advice would be helpful if its something easaly fixed or not.... thanks i am a tech just a fyi