Got a 1996 Tahoe 2dr. 4x4...Tried to pass some one today and mashed on the gas and my ho revved up but wouldnt go. Something in the tranny is slipping i think. If you ease on the gas it goes fine but when your already moving & gouge on it something slips. THEN MY CHECK ENGINE light came on. checked the dtc's & got P0131 & P0151. what are these? please help?