Idle Problem
 

'88 mk3 non-turbo. My engine normally idles solid around 1000 rpm but has randomly begun to idle lower and bounce between 500-750 rpms as it misses and fires. It seems to do it more when it has warmed up. I was told this may be a bad fuel filter but it sounds like a real pain to get to so i was wondering if anyone had experience with this sort of thing. I would apreciate any info. Thanks.