I have a 2000 Yukon XL 4x4, I love my truck, but I am having an issue with it. When I start the truck and go to drive off, it hesitates and doesn't seem to want to give me the full power I need to get up to speed, even when I put floor my gas. The RPM will go up to about 4 but yet i am not getting the power to drive it the proper speed limit. If I pump the gas for a few blocks it will then kick into a higher speed. Also sometimes, the darn thing just won't start, yet it is not flooded. For the past year and a half I have spent thousands on this problem, I have had the fuel pump replaced, all the filters replaced as well as the bands. I have had about 8 diagnotic tests done, and they can't find anything wrong with it, and when I have left it at the mechanics they never seem to feel the hesitation, and tell me it must just be my imagination. Well I know it isn't my imagination. I have taken it to 4 different shops and yet no one can find a thing wrong with it. Does anyone or has anyone ever had this problem, and had it actually repaired? Please this is starting to drive me mad, trying to convince mechanics there truly is a problem with my truck.