Engine hesitation until full throttle

It sounds as though you possibly have a malfunctioning throttle position sensor. If you take your vehicle to your local AutoZone or Advanced Auto Parts they should be able to hook it up to a diagnostic machine and retrieve any codes generated by the engine control module. There is usually no charge for this service. They'll also be able to translate the codes, indicating in which areas there are problems. After that it should be a simple matter to troubleshoot any malfunctioning systems.