I have a 2001 Toyota Corolla that is running too lean and misfires (from code readings). I have to use starting fluid 90% of the time to get it to crank now. It will turn over on its own but won't start. Also, when it finally cranks I have to rev the engine to keep it on and when I come to a stop, the car shakes and stops. If I keep the RPMs high enough when I stop, it usually won't die. I have replaced the fuel pump and spark plugs so far and will be replacing the fuel regulator, fuel injector o-rings (because they were dry rotted and there was a severe gas leak coming from fuel injectors), and cleaning the MAF. I also noticed a valve cover leak when I changed my spark plugs. I have narrowed it down to my fuel system but would like to know of any greater issue I may have. My engine also knocks and every week or two of not putting oil in it, I am 1-2 quarts low. I have noticed the smell of gas fumes in the passenger compartment while I'm driving. Please help, this is my everyday driver vehicle. Thanks!