Shift shock/ cpu re-programming
 

First I have a 2006 Altima and every now and then, and only during moderate acceleration my transmission slams into gear. Almost like someone is hitting the bottom of my transmission with a 10lb hammer. I have 6000 miles on the car and it has happened about a dozen times. I can't make it happen when I want it to, not that I want it to, but to that the dealership can't fix what they can't see, hear, or experience for themselves. I have been told by an employee of nissan that later model maximas had this problem as a result of lack of fluid to filter/cell chamber of the transmission that holds the fluid. As you may be able to tell not a transmission expert here. I'm just wondering if anyone else has been having this "Shift Shock" problem as it has been refrenced to me with there vehicle.


Second, I have also recently installed a K@N cold-air intake and a Magna Flow catback exhaust system to my car, and was wondering if theCPU needs reprogamming or if it is self calibrating. I've noticed that my mpg estimator has gone crazy and a slight greyish smoke in my exhaust with the hint of unburned gasoline. I would really appriciate any input on either one of these issues.