I have a 99 Chevrolet with the 5.3. I can go out in the morning and it will fire right up. When I drive it for a while and then cut it off and then go back to crank it, the engine turns over and over and then when it fires the engine hesitates before coming to regular idle. It runs like normal on the road once it comes to regluar idle I took it to the local dealer and all they did was clean my fuel ports but it did absolutely no good. Is this problem due to the injecion pressure regluator? Thanks...