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I've searched far and wide and have no idea what's wrong. I suspected the AFM, but that's fine, O2 Sensor's are fine as well as they have been recently changed and I just cleaned the AAC valve less than 2 months ago. I've replaced most vac hoses and there doesn't seem to be a leak... Also, the spark plugs are new, gaped at 0.8mm and the coilpacks are fine and I'm only running 7psi boost anyway. The rough idle started when I removed an aftermarket boost gauge and plugged up the vac line going to it.

So what is happening is, when I start her up, she sits on her normal idle for about 10 seconds, then she starts choking, and drops down from 850 to 500 and back up to 850 and this repeats until however long it takes for her to catch. I can rev her up a little and make her catch but she will splutter again and again. Driving her seems fine, no problems what so ever, it's when she gets to slow speeds (5km/hr or under) or idling it starts to choke and splutter. I have no idea what's going on :( and it's really annoying me. Any help would be grateful! Thank you in advance.

EDIT: Will also mention, she isn't blowing any coloured smoke, no black, no blue and no white, she is running fine. Injectors sound normal as well, and there isn't any misfires of any sort. Temperatures are fine and the stuttering and spluttering happens anytime it's at low speeds or idle, it's worse when it is cold (obviously).

Edited by ZiAzon
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https://www.sau.com.au/forums/topic/418742-r33-gtst-auto-rough-idle/
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  • 2 weeks later...

Found the problem, when the mechanic went to change the condenser out for me whilst I was at work, he forgot to plug in one of the vac lines and because it was black on black, it was almost invisible -_-

TIP FOR OTHERS: CHECK ALL FRIGGIN' VAC LINES TO SEE IF THEY'RE CONNECTED!

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