Loss of acceleration from stationary

[Shodz12]

Hi all, 

i drive a 2005 focus 1.6 lx auto.

i have this issue where the car drives okay, not great, and then from stationary when i try to accelerate, i have no power. i would press the gas pedal a few times and the car wouldnt move and then after say 5 seconds the power comes back. 

i had my cat checked and mechanic said it was okay so changed the o2 sensor. Also changed the coil pack and spark plugs.

Has anyone got any ideas why this happens.

Also i get ridiculously low mpg, it was 20 (which is bad anyways) but now its dropped to 14.

and last problem i have is that when im driving, suddenly all dash lights would come on and the gears on the dash would start flashing. Also says ‘engine system fault’.  Any ideas?

 

thanks in advance