starting/driving problems

Hi, wonder if anyone can help me.
I have a Discovery 1995 TDi.
This has only just started to happen.
When i start up in drive sometimes there seems to be no power, even when i press down on the accelerator. It then goes to a normal idle, but as soon i put it into gear the same thing happens. No power even when pressing the accelerator. Back into park, couple of revs then it goes. Its hard to explain but am worried that there is a major fault.

Thanks

you start in drive?? you shouldn't be able to do that.. when you say "no power" do you mean no drive or that the engine dunt rev?

Sorry i start i park your correct in pointing that out.
Yes there seems to be no power in the engine. Eventually it goes, but also noticed that when i stop sometimes the same thing happens, it hesitates.
Blocked injectors?

Thanks

think you'd want to start by changing fuel and air filters or at least checking them int blocked

Just started it.
In park idling fine as soon as i put gear, power goes, back into park a few times then all goes ok.
Weird.