Mickey,
Had this problem on our 95 UK Wagon, it was down a the temperatre sensor, sensor is accessed from the drivers side of the front wing and is located under the inlet manifold, from memory had a brown connector on the cables.
I think a new one cost about £25, fitted it myself, seems to be quite a common fault & dealer had a sensor in stock.
You may find it a little awkward to start in the morning due to the sensor being faulty the ECU will think the engine is warm but she will start.
Not saying this is definatly the fault but seems to have the same symptoms as ours did.
Hope you get sorted
Paul