It has the 4.8L v8 engine, now the problem is intermittent some days it shifts perfectly while other days it shifts hard all most like when you shift late. then when I'm in 3rd or 4th gear it bogs down my rpm by 200-400, and if i engage the cruise control turns itself off when the bogging start which is about every 5 seconds. also when i hit the breaks my instrument stay lite but the gauges drop to zero for about 2 seconds then they go back to normal, I'm wondering if they are related problems. all my fluids are good, and the crazy thing is the service engine light is not on when the problem is happening furthermore when i took it to auto zone to have it scanned there were no stored codes or active faults. Please anyone who has had this problem or knows about Yukon's share the knowledge