Crank no start?

I have a used ambulance E450 two days ago when I was in traffic light the engine start shaking RPMs go up and down accelerating slow, I turned the engine off crank again everything went back to normal. The next day I cranked the car would not start. I have checked diesel pump oil pump injections were in normal range. I thought may be fuse or relay but since I have lost the user manual can u help to point which fuse or relay should I check and their position in the fuse box hoping this might be the problem or you suggest something else?
By the way I used start spree in the intake but no start also
Thanks a lot I will post the car picture.