2001 Toyota Echo Starting Cold Engine

Engine Performance problem
2001 Toyota Echo 4 cyl Front Wheel Drive 148000 miles

If my echo has sat for a period of time (say 4 hours or more), and I try to start it, the engine dies immediately. It will continue to do this until I start the engine with the gas pedal slightly depressed. Once the engine has started, the car performs as always. Once the engine has warmed up, the car starts in its normal fashion (for example--running several errands). If, however, I go to work and let the car set until lunch time, I need to start the car with the gas pedal pushed in again. Any ideas? If you have an idea of what the problem is, could you give me an idea of the cost? Thanks.