spluttering at low revs

[the chief]

hi guys, my cars just started playing up! when i drive it with low revs and in vacuum the engine splutters and also idles crap. but when it goes in to boost it runs fine. today i changed the plugs, leads. rotor arm and cap, and the lamda sensor and but it still the same. no fault codes. cant hear any air leaking out. my car has a hks fuel controller, could it be this playing up? when the cars on boost it runs fine.
cheers guys

fixed
broken fuel controller!

 

[kirko]

check your injector plugs/connections mine came loose as there are no clips to hold them on
and was doing similar to what you describe

 

[the chief]

checked all that and changed the map sensor and afm and its still doing it. the fuel controller has a eids light that comes on when it splutters and stays on for about 10 seconds when it idles.
its doing me head in!

 

[Fusion Ed]

what is the idle vacuum?

 

[the chief]

what is the idle vacuum?

what its always been. went for a short drive today and the fuel controller is displaying double the revs! at idle its showing 1800rpm and the rev counter is showing 900 and at 2000 its showing 4000rpm.