GM Certified Pre-Owned 2008 TBSS w/7773mi bought on 4/9/2011. During initial drive home thought I was babying the accelerator pedal having owned a 2002 TBLT, 2004 TBLT & 2008 TBLT feeling a hesitation when accelerating from a STOP or when emerging from a street corner turn (having slowed down to an acceptable turning speed). Two weeks and a couple of tanks later having read the GM Owners Manual I thought my concerns may have been due to the fact that I was using Regular Unleaded 87 Octane vs. 91 Octane (Owners Manual recommends 91 for 6.0L V8). Three tanks of 93 Octane later, still feeling the hesitation. A friend pointed out that today's engines don't rely on Octane ratings as much as older engines. The computers will make adjustments. As long as I'm NOT feeling or hearing a "ping", 87 Octane won't hurt the engine. Well, still feeling the hesitation, I brought my TBSS to a dealership, not the selling dealership (they're over 100 miles away). Dealership recommended changing the air filter, a throttle body service and fuel injector cleaning. I had them do the recommended services. Upon driving off the lot, I could still feel the hesitation even thought the dealer claims the TBSS is running as expected. The service advisor recommended I take the TBSS on the highway at least once a week and "open her up". Let them "ponies run". I have a friend who races and build's cars. He has yet to drive my TBSS but feels that I need to "floor it" every now and then to burn/clean any carbon or other deposits built up in the engine. I've been driving cars for 30 years, I'm 48 years old, and I've not felt a vehicle hestitate like the TBSS does. I'm not sure what else I can do other then bring it back to the dealer that did the service and test drive it with one of their mechanic's. Any thoughts or advice would be appreciated and helpful. Thank you in advance.