Mk4 Gti new owner in need of advice

[Djemery]

HI ALL,

Just bought my 1st vw golf gti 1.8 1999 and encountered my 1st problem and would appreciate any advice before having a weekend trying to sort it.

Problem.

Car idles at 2000rpm when stationary,  rev count fine when driving.

Hoses seem ok.

slight smell of fuel in engine bay, could it be the MAF sensor faulty if air and fuel mixture in correct causing high idle, at a loss as no engine light on, so diagnostics not picking up a fault.

Many thanks

[Mr_Orange]

Is this an AUM or AGU engine code? 

AUM has an air pump that kicks in from cold and last for about a minute, before idle settles down to 800rpm again.  Could also be the throttle body is dirty and requires a clean and re-alignment.

If AGU that idle is way wrong. Should sit at around 800rpm.  Its on a spring so should just return to closed position.  I'm not too familiar with that early throttle configuration, but it shouldn't do that. 

Smell of fuel in the bay is rather worrying.  That and the crazy idle could all be indicative of a vacuum leak.  There's numerous hoses that can perish over time.  It can usually be traced by spraying of WD40 around everything until you hear the rpm drops, that there's your leak chap.