I've recently been having an issue when starting my car. It turns over fine but then drops from 1000 revs to cutting out. It can take more than half a dozen attempts to get the car running and white smoke comes out when it does. The engine won't rev either when you press the accelerator. The car has 109000 miles on but has been fully serviced and has also had egr/dpf mod and remap in the last year. Any suggestions?