Hi again guys,

Sorry If I'm posting this in the wrong thread, fairly new to the forum and can't seem to navigate well around it yet

Just wanted to ask everyone's opinion.

Yesterday as I was driving through traffic on Canning Highway after work, something rather unusual happened for the first time, basically the car idles at 2100 rpm even at red light and when I had my foot on the brake.

Just suddenly happened and I feel a slight vibration on the clutch, when I engage on the clutch and pedal the rpm drops to normal just after 1000rpm and goes like normal but then when I slow down again approaching traffic it would again for no reason jump to 2100rpm with my foot on brake.

Again throughout this whole experience I feel a slight vibration on the clutch pedal.

Once I get to my destination, switch off the engine and 15 minutes later turn the engine on and drive again, it's normal and hasn't happen again this morning (everything was normal).

Any idea guys what could be the issue? my guess is not having a proper tune?

Quick summary, it's a 99 WRX, mods done is TBE, GD STI TMIC conversion and Manual Boost Controller.

Any ideas and recommendation is much appreciated

Thanks again guys.