wont rev over 4000

I recently changed the crank case filter and the air filter at the same time(2003 TD4).
Looked like a fairly straight forward job before I started.
My problem is the car wont rev above 4000 now I did have an issue with the car not starting yesterday but this morning stated first time chucked out some smoke a spluttered a little bit but then all seemed fine.
Apart from the loss of power at 4000 the car runs normally.One mistake I'm sure I made is taking off the injector fuel line.

Mine would not rev past 3500 it was the fuel pump