Lose of power on a mk1 intermitent

[Stubbsy999]

Hi i have a focus mk1 03 plate auto 

car had idleing issues but managed to find the vacuum leak and change the the pipe where the pcv valve is at the same time ive changed the air filter 

fuel filter, spark plugs and cleaned the throttle body and iac vavle  and changed the o2 sensor 

but for some reason car loses power now and then on the peddle 

any ideas ? 
oh and i have a diagnostic machine which is how i found out about the o2 sensor now the car has no codes no fault lights but still have this issue

 

thank you in advance