Recently noticed car has started to shudder when idling and exhaust seems to make a sputtering sound when ticking over. The car occasionally stalls and is sometimes hesitant when pulling away - usually after changing up to second. Very occasionally, when changing down e.g. stopping at junctions, engine might slow down and sounds like it's about to stall but then picks up to idle speed ok. This has only happend only once or twice. Have recently had car serviced and mechanic told me he thinks it's misfiring on no. 4 cyliner. Not sure if he looked into this in much detail. Amongst other things he told me timing belt needed changing, new clutch cable and new OSR wheel bearing were needed. Have now done these three jobs myself but unsure about the misfire problem. Mechanic suggested misfire might be a leaking valve seat in which case it would be a big job to sort out. Is this really the only likely cause (car only has 70k miles)? A friend of mine has a compression tester so we are going to run compression test on each cylinder to see if there is a seal problem although not sure how helpful the results will be. My understanding is that low compression and misfire could be caused by one of any number of problems. How do I narrow it down and what are the chances of being able to sort this out without handing over vast sums of cash to a proper mechanic??? Have also had someone suggest this could be caused by leaking vacuum hose, is this a likely candidate??? If so, is there an easy fix???
1992 Golf Mk3, 1.8 GL, 70k miles, Engine code ABS, all useful advice appreciated!