sudden power loss when driving?

while driving I found no response when I press the accelerator pedal the car slowed down and I pulled over. Turned ignition car started. this happened three times in 3 miles. I then stopped for ten minutes and when I tried to start the engine the engine did not turn over all I heard was a click every time I turned the ignition Key. I got the Jump leads out and tried to Jump it off another car. Would not start just clicking. It was raining at the time so I decided to look at it the next day. When I switched on the next day it came up with a message, "now in economy mode" Turned the key and car started and drove home . Has any one any Ideas this is not the first time