Decided to take our bus out for the day on Sunday as it hadn't been out for about a month. It's a 1979 Westy, 2 litre. We had already been travelling for about 30 miles and had been cruising along at 60mph for about 15 minutes when I felt the bus 'cough' a couple of times. It immediately lost a bit of power. Over the next couple of minutes it continued to slowly lose power until I managed to pull into a layby a couple of miles further up the road. By this time the bus was struggling to do 30mph. Being a mechanical numpty I called the AA. On arrival the AA chap checked a few bits but couldn't find anything obviously wrong. He said that we had a good spark, and sprayed some WD40 in the distributor cap. He decided we should give it another go, and followed us a couple of miles to the next junction. The bus was now behaving fine. He said that maybe we had had some moisture in the distributor, although this is would be unlikely after we had already driven 30 miles. He also said that it was a sign of the condensor packing up, but once they start causing a problem it wouldn't have suddenly got better. So he wasn't sure what had caused it. We made a decision to carry on with our day out, and the problem did not re-occur, although I deliberately did not go over 50mph for the rest of the day. Does anyone have any thoughts on the AA man's comments, or any other ideas about what might have caused this? Many thanks folks!