Engine Exhaust System problems of the 2004 Nissan Maxima

Good morning, I currently own 2004 Maxima & have been experiencing major problems with this car for about 2-3 years. My major problem at first was my transmission. Apparently the dealership states I will need a new transmission which is absurd since the car is not even 10 yrs old. I knew there was a problem when the car started jerking on its own. At times it jerks real hard when shifting from 1st to 2nd and it is quite scary & embarrassing. When the problem started, I have two friends who were owners of a Nissan Maxima as well and they were experiencing the same jerking transmission problems. They eventually traded their cars but I not wanted to go through the whole process of financing a car, I figured I'll fix the problem. The transmission is one problem but why every couple of months there is other problems as well. For example I last year I had to change my catalytic converter, my mounts, and my routers. Now what has made me at my ends with this car is what happened last month (June 2009). While driving, there was a loud sound, I opened the hood of the car and right buy the engine, and there were flames. The fire dept was called along with the police. As I submit my complaint now my car is still at the shop. This has become a frustrated and very expensive issue that I have been facing. Honestly I have spent about 5k's or more on this car, not considering that I'm still financing as well. How is it that, I have done my research and there are many others out there who have the same issue. Nissan needs to take full responsibility and it is not a coincidence also. I have documents and emails from others who are also experiencing the same issue (over 300 complaints since 2006). Pls if anything, there needs to be an investigation, many ppl are suffering and losing $ as well.