Vehicle Shudder problems of the 2006 Nissan Maxima

I have a 2006, Nissan Maxima se. I've been having severe problems with my transmission. The car jerks violently when its changes gears between 1st and 2nd, as well as between 2nd and 3rd gear. After doing research on this problem online, I've seen countless number of people who complain about the same problem. I re-built the transmission at my expense of $3,200 and it wasn't over yet, then currently my check engine light is on and my car wont start, I would have to turn the key on and off 4-6 times every time I need to drive for it to start. My speedometer stopped working, therefore I can't see how fast or slow I'm driving nor is the mileage calculation are working it has been stuck at 86,745. So many people have experienced this problem from 2004 to 2008. I don't see how this could go on. While driving on the highway the electrical fails and the lights on the dashboard dim to where I am not able to control the vehicle and unable to use my signals for safety concerns, especially while traveling at night time. The vehicle shakes and is unstable at times. This is my only transportation to and from work and I need a solution to this problem. The sad part is that I have taken it to the dealer four times now and every time I pay these high fees for diagnostics and they can not give me a solution to my problem.

I have a 2006 Nissan Maxima se that I bought new in Jan 2007. Several months ago I replaced the oem tires because I was old they were worn out and were the cause of steering wheel vibration above 60mph. I replaced the tires and front brakes/rotors at my Nissan dealership and the vibration was reduced but still noticeable. It gets worse with cold temperatures. They have inspected the struts and engine mounts and say there is nothing wrong with my car but the vibration is still there.