About fuel injectors?

<>Injectors can get clogged from dirt and crap in the fuel. However, you said that "shaking the fuel filter" solved the problem, but changing the fuel filter did not. It sounds more like you have a problem in the fuel lines (a rust blockage or something similar). I would suggest dropping the fuel tank and blowing out the fuel line (or, if it is really corroded, changing the fuel line). While you have the tank out, clean it out thoroughly (and consider replacing the fuel pump if you don't know how old it is).