Thanks for the info....
My arduino is doing other thinks beside measuring the amps from the acs714, like sensing batt voltage, controlling some relays and outputing to serial the information...
because of this i have some "delays" how can i keep in main loop doing all other stuff and at the same time read "1000/sec" that value ?
ARduino multitasking 
.. i will have look on how to accomplish this ... any tip will be useful regards.
Can you please explain better "Sum these samples and scale the result according to the time between samples and you have a value that is the total energy over time" ?
regards.