I recently bought a 2000 Pathfinder diesel pickup (2.5L) I drove it home and it was going ok for the first 2.5 hours, but for the last hour it started losing power and would not rev. I had to stop and when I tried to start again after a minute or so, the revs came up, and also a cloud of blue smoke from the exhaust. The same pattern repeated itself for the rest of the journey and I was relieved to get it home.
What could be causing this problem?