hi guys, car starts fine, but when idling the rev counter cant stable itself it revs up and down slightly by itself, as soon as i accelerate in neutral it returns back to its normal position where it should be but even still its not completely stable. some people have told me to get it re-tuned? others have told me to clean the IAC valve, im not sure where or how to clean it could anyone help, thanks alot. also if you know of any others probs it could be hit me up!

is this an my99 wrx?

it could also very well be your AFM

yh its a 99, AFM? sorry new to the car haha

When mine drops to ~1300 rpm, it revs itself back up to ~1600 and then drops again, then revs back up again. No idea what causes it. Doesn't do it on cold starts, usually does it when I stick it in neutral, and sometimes when I'm driving between 50-70 and take my foot off the throttle, it does it as well. Is yours similar?

Interested to find out what the hell causes it.

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It's at the corner of get a map, and fuck off

i'd say dirty or faulty AFM, my old GC did it and i replaced the AFM and all good, my Liberty is currently hunting/unsteady at idle and it too needs an AFM.

oh yeah and AFM = air flow meter, attached to your air box/air intake

the solenoid in your throttle body that regulates the idle, is dirty or seized, and needs a good clean or if its really bad replacement.
(its a little bit ontop of your throttle body, (coolant runs to it on mine) take it apart and clean it/unjam it/replace it. but its kinda hard to explain, and im at uni atm so i cant get a picture, but yeah, if you keep driving around, it might vary heaps, from normal, to a little bit of antilag spec, to the point were its nearly undrivable, lol and you might get an engine light)

subaru will tell you that for 147, and fix it with a new one for ~700 lol.
second hand ones are about ~400
but i bet if you take it to decent garage, they can sort you out.
maximum helped me out
i put a thread up on here somewhere, but i couldn't find it, but yeah if you still need help, pm or 0437380338

yeah they are different on gc8, no coolant passes through it, 2 phillips head screws gets it off

yep --- easy peasy japanesey. Get some brake and parts cleaner and remove that solenoid. Clean it with cotton buds when you spray that stuff on. Then put it back and hopefully the problem goes away. Do that first, otherwise it will be the AFM.