I have been researching this and have found more than a few possible causes but I am hoping someone may be able to narrow it down for me. I have had a fuel trim low load upper limit error as well as one referring to the fuel being lean. the odd thing is that the hesitation seems to be the worst when the fuel tank has been filled. On a lark I did replace the fuel cap. At time the hesitation is so severe that the car just creeps then suddenly "kicks in". It cuises fine and once it finaly decides to go it accelerates great. Any help would be appreciated.