I am new to posting and came across this problem so I am asking for some "HELP!" I got a very good deal on a 2006 STS 4. I recently took it on the road to FL from NY and started getting this clackitty noise form underneath the car around the center. Mostly form the front of the car, but sometimes from the rear (especially from rear on turns) After the noise the car catches and is smooth as silk. It returns when I try to pull off from a full stop and sometimes when I'm cornering. Always after the noise, smooth as silk. Growing up being called "Mr Goodwrench" I am somewhat of a do it your self type. There is no clanking when the car is still. Even when I shift form D, N to R and R, N to D. The torque it takes to move forward 'quickly' and I discovered up hill, produces it. Sounds like a gear trying to catch. Anybody have any idea what I need to have adjusted or replaced. I returned from FL like this, practicing slow take offs and hope that it"s not anything major.