ROVER 620 2.0 SDI 1998 (Honda Accord 98) start problems

Brand: Rover (Honda Motor, the same of the same year)
Model: 620 SDI
Year: 1998
Kilometers: 300,000
Suitable: 2.0
Power (CV): 105
Fuel: Diesel
exchange rate of marches: manual - 5

very good speeds, to see if someone can guide me/help me with the car (which is a clone of the Honda Accord of 98), which has been doing badly, which has come to start in years. Garage all his life until 5 or 6 years ago on the street. As I say, for 8-10 years when winter arrived, it began to cost him, based on activating the heaters several times and trying several times, he ended up starting without too many dramas.

But over the years it has gone worse, to the point that even activating heater 6 or 7 times when it takes the contact between 10-18 sec to start, pulling enough white smoke. (The colder it takes and when the more temperature is, the better it starts)

for a few years I move 3-4 days a week of average, about 6,000-10,000 km a year, with a couple of long trips a year.

The curious thing is how much the start with the temperature varies, since if I start in hot it is perfect or parked where the sun does not start perfect, but infinitely better, when it has frozen it is a drama, however ...

it has heaters, battery, all the filters and liquids changed and continues to happen exactly the same, the ITV passes it without problems too. After investigating a lot, I have reduced the problem options to: dirty injectors, obstructed admission, compression loss of one of the cylibdros, diesel pump or flowmeter. In the workshop they have told me that perhaps adding a heater in the air intake as they have other cars the problem is solved, but that without reviewing everything else is impossible to know.

In the end it is a 22 -year -old car, I do not intend to always go perfect and although I have "retireing" several years, it seems stupid to change it for the use that I give it and I do not mind getting hand myself because if I take care it would not be a drama!

I hope I explained without being too rolled.