My 940 turbo left me stranded about one month ago. Totally dead. It would crank, but not turn over. I had it towed to the local mechanic, who had a Volvo tech look at it. He replaced the crank sensor. The car ran fine for two weeks. Now it has developed a "tick" in the tach. At idle the tach will ramdomly jump between 1000 and 3000 rpms. The car does not feel like it is idleing this fast. It also has a light stumble every now and then. Also, there does not appear to be any rhyme or reason when this occurs. Does anyone have any ideas on the cause? All help will be greatly appreciated.