Need help with a problem that I can’t figure out. So my mk2 vrs is running rough on idle but when the engine is warm the idle goes up and down. I’ve had it to a garage more than I can count, they’ve found nothing. It’s Been to an auto electric’s twice, I’ve replaced 

throttle body

cam timing magnet 

cam bearing housing 

coil pack twice 

plugs twice

Pcv valve 

hpfp

evap valve

cam sensor 

injectors

fuel filter 

and still no change. Can anyone shine some light on any problems thanks

Oh and the codes I keep getting are

P0507

P0171

You’ve most likely got an air leak, the PCV system and inlet pipework need inspecting for leaks.

 

is the garage your using reputable? It’s not a main dealer is it?