i've just bought a mk2 eight valve and tho i was gonna sell it 'cos i wasn't keen-it's started to grow on me, it's just begun to stall at tickover and it seems to be 'hunting' real bad, i got caught out and had to put unleaded in it-which coincided with the sh!t running, could this have caused it or is it likely to be something more sinister--also it needs a new clutch-how much should i expect to pay? thanks in advance