When I start my car, it revs for a split second but drops and dies, so I have to hold the gas and warm it up before I can release the gas without the car dying. Still it barely holds above 400 rpm, when it should be holding at 1000 rpm. This happened once 4 years ago, and the Toyota dealership replaced my entire fuel injection system. This time I took it to a mechanic who replaced the computer that regulates air and gas flow, which fixed it for 3 days. They also replaced my fuel filter. Now the problem is back.