Just bought a 250 from a auction and it ran perfect on the lot but started acting up on the way home. I can slowly rev the motor and its fine. If you mash on it it runs up to 3000rpm and shutters and smokes raw fuel. I changed the fuel filters today and its better but still doing it. You can hear the turbo spool but not sure what it could be. This is my first diesle so dont know where to start. No check engine light or anything.