Is it common for high idle with missing vacuum hosing. Replaced battery with new one and when I started on cold 1200rpm and warm 1800rpm. Car has been sitting for couple of months so may have lost on its way somewhere. I don’t want to go ripping anything yet. I just want someone’s opinion.(see pics)

 

That looks as it it's missing the coolant hoses to warm the iacv/throttle body or it'ss been bypassed.

 

It’s strange, not my build so I’m trying to fix the cause. Any reason why is was bypassed in your opinion

 

To stop hot water circulating round the throttle body and the throttle plate sticking in cold climates. It'll be spot on here.

 

So I figure I best start with a clean of the air control valve

 

 

So after having to wait a couple of days for a new rubber gasket, and on top of that who ever invented Torx screws needs to be shot.
very soft, that includes the two Phillips screws holding in place. I ended up mangling the two Torx screws, if if ever happens to anyone quick fix is to use a grinder and make a line enough for a flat head screwdriver, then replace. Degreaser and cotton buds for the cleaning, RPM now back to normal. Thanks for your replies

 

Before going anywhere near any of those fastenings a wee tap with a hammer and the appropriate tool and they generally fly out

 

Update,
went for a drive last night everything was in working order. When I came to a stop rpm was fluctuating any help appreciated can’t seem to upload file. Goes up and down between 900/1100rpm

 

What year is it.

 

05 JDM STI

 

Generally the mafs don't give too much trouble with the newage cars, have there been any mods done other than that possibly o2 sensor if you haven't any air leaks.
Also check the bov and is it oem or aftermarket.

 

Bov is oem,
I did check maf sensor it does appear dirty, New Year’s Eve no place open to get cleaning product.
no mods done apart from turbo timer months back

 

Well turbo timer is a waste of time on a Subaru. Try cleaning it with petrol and then a careful blow with airline.

 

Thanks Joe, I’ll revert back. Turbo timer personal preference. 😅