2007 Nissan Altima Need car fixed

First test the #3 fuel injector with a noid light. That is simply a bulb with a positive and negative lead and touch the leads to each injector wire. Turn the engine over and if it lights up the injector is working. In regards to the Sea Foam. It can actually make the engine perform worse for a while after putting it in your tank. It loosens deposits which eventually settle into the oil pan, but can clog ports until they do so. So, give it some time and maybe even run another can. If you want something that really works well, BG44K can be purchased at most car dealerships at the parts counter. It is $20 or so a bottle but it is the best fuel system cleaner. Sea Foam is good as well. I do not think any other fuel system cleaners work like they do. Be prepared to change your oil after this as the carbon deposits end up in the oil pan and dirty the oil.