XJ 8 Difficulty starting from cold.

Recently it's been difficult starting from cold. The engine has to be turned over more than double the normal time, before it'll start and the accelerator has to be used to keep it running above 500rpm, otherwise it'll stall. Have looked at the MAF & Temperature sensors, but they "look" clean and undamaged. The MIL lights don't show any problem. Otherwise the car is running OK. It's just the bad starting from cold. The car is based in Scotland, with an average temperature recently, in the middle 40f degree range. Can anyone throw some light on it. Also can anyone recommend some reasonably priced diagnostic tool for this model, using a Laptop.