The cam and crank position sensors seem to be a common problem among cars equipped with the VQ35. If its possible, you should have it checked with an OBDII scanner. I once caught the Ford/Mazda dealer in town trying to pull a fast one w/my brothers car denying warranty work when his mazda millenia with only 23k miles had one sensor after another sensor failing. The dealer first stated that AutoZones scanner was faulty, then he said O'Reillys scanner was faulty, then said Advance Auto Parts scanner was faulty. A quick call to one of the Ford/Mazda corporate places solved the problem and the car was traded in for a Nissan after only 9 months of ownership.
They don't call them the stealership for nothing. |