Discovery 300tdi blue smoke running erratically

Hi everyone, i am a new boy who is in desperate need of help. I have owned my disco now for 3 months with no problems. i have changed the timing belt 4 weeks ago, all is well. Untill thursday when it started to miss. this has gradually got worse until today it will not run properly and produces blue smoke. I have also had it running once today normally, very strange. i have changed the fuel fillter, lift pump, cleaned the sedeiment bowl and checked the top has not rotted. Do the breathers get blocked! thank you for taking the time to look.

stuck waist gate

do a search an see if it fits your problem
but i'm sure stuck waiet gate causes blue smoke
just bare in mind i might be talkin bollox

Does the engine rev freely,if not is belt timing correct?