Why would a escort 1.8 TD van be very slow at turnover from stone cold but when its warm be as it should be and start no problem with plenty life ??

It has a brand new battery, and heat plugs have only done 5/600 miles (They were changed but it made no difference as its been like this for over a year but its sat un-used for 1 year)

Pump and injectors were done (refurbed i think) by the previous owner before my mate bought it but was about 3/4 years ago but van has only covered a 3/4 thousand miles in that time.

Could it be the pump or is there a cold start valve or similar needing replaced ??

It takes maybe 3/4 heats of the plugs and sometimes this is twice before it fires into life but it is very slow and door lol

many thanks