I would suspect the clutch is not fully disengaging , the first place I’d look is ( assuming it is a hydraulically actuated clutch ) is at the fluid reservoir to see if it is full . If the level is low , that could point to a leak in the clutch hydraulics .
Some of the VW cars we have had in the past had cable operated clutches , and if the Mk4 has a cable , it may be out of adjustment.
After that you could be looking at the clutch release bearing , but this will involve removing the gearbox , at which point you would be as well renewing the clutch disc , cover plate and release bearing . If there is a slave cylinder , and if it is inside the bell housing , you would be as well to change that too since the cost of these components is not high , while the time and trouble in removing the gearbox is a greater consideration .
I remember replacing the clutch in one of the Mk2 Polos we had , and it was enough to disconnect the driveshafts , remove the starter motor ( after disconnecting the battery ) , undo the gearbox mounting bolts and slide the gearbox to one side .it was a long time ago , but I recall then having enough clearance to do the job without needing to completely remove the gearbox . The clutch cable then had to be adjusted so that the clutch would fully disengage , and that it was fully ‘in’ with the pedal released , hence the release bearing fully released .
I also did the same job on my Audi 100GL and on a Passat GLS , essentially the same job .
We had later Golfs in the family ( everything from Mk1s to Mk6 ) but I can’t recall when , if at all , they moved from cable operation to hydraulic operation . I never did as much work on the later ones .
