2000 ford focus se stalls while driving. i have replaced the ecm, throttle switch, air filter, and battery.

i will be driving down the road and my foot is on the gas pedal then all of a sudden it feels like i accidentally hit the brake even though i didnt. then after that the car will stall. its stall while sitting at red lights or stop signs but it will also stall while driving down the road. i drove it today and in a 10minute drive home it stalled 4 times!