Renault Megane mk2 2003 1.4 16v expression startup and loss of performance

I'm no mechanic
Got problems starting the car have to keep my foot on accelerator or it sometime dies but after 10 seconds or so its alright
Sometimes Rev counter jumps up and down on its own

And when pulling of in low gears there seem to be no power or sluggish but when up to speed limit its ok

Things I've done brand new spark plugs and set of coils no different

New oil and oil filter change no different

Cleaned throttle body out to nearly new no different

New injector rail no difference

It's a Renault Megane mk2 2003 1.4 16v 5 door

Plz any help would be great
At my wits end
Plugged it up to computer and got some codes
Misfire random / multiple
Misfire low fuel

Thanks

Renault Megane mk2 2003 1.4 16v expression startup and loss of performance