I have a 01 Silverado 4.3 v-6. While increaseing speed slowly from a start or while moving above 2,000 RPM's I am getting a lot of hesitation. If you floor it it goes away. If I am on the highway and trying to maintain speed it does it as well over 50 mph. I have replaced the plugs, wires, rotor, cap and the crank position sensor and all 4 of the O2 sensors and it is still doing it. I am not sure if this could be from the distributor or from the spider injection and I have dirty injectors. I have ran a couple bottles of injector cleaner through my tank over the last month and still haven't seen a change. Any help would be awesome.