I bought a discovery 300 tdi a few weeks ago as a project to get on the road but there is a idling problem when you first start it up. when you start up it will idle so low if it idled any lower it would stall, when it runs for a few minutes it will idle at about 1500rpm. when you slowly pull the clutch out it will go back down to 500rpm and stay there after you put the clutch back in until you rev it again. I have adjusted the throttle cable but that's not the problem. anyone knows what is wrong????????? thanks

Check fuel filter and air filter there is also a water trap thingy fixed to chassis near drivers side back wheel and may be worth checking injectors.

not sure but i think that the injection pump has some sort of cold start that advances and retards the timing depending on temperature that works with a spring inside the pump.If you google Bosch VE pump internals you should be able to see inside the pump and determine whether this is your problem or not. It could also be something as simple as clogged filters as mentioned above so change the fuel and air filter first and then clean out the sedimentor. I would only suspect the pump if it runs like this when either hot or cold but if it settles down and runs ok when hot then it wont be a pump fault.

ok thank you for your posts