check light on,cod p0300 miss fire,poor running at idle,last point before i scrap,throttle body clean,????

hi, just replaced air/oil sep,plugs,coils,on my 1999 2.7 still problem,on the road cars ok,let it tick over, check light on,cod p0300 miss fire,poor running at idle,last point before i scrap,throttle body clean,???? then scrap,can not get, NEW MOT WITH CHECK LIGHT ON,

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[Nick at Pelican Parts]

Throttle body cleaning would be nice. Try running the engine at 2500rpm for 5 to 7 minutes to pump up the lifters and see if it runs smoother. You may have a vacuum leak causing the poor running

- Nick