K10 1.2 engine cutting out.

My normally utterly reliable 1992 Micra K10 has developed a curious but only occasional fault. I drove from Whitstable to Brighton recently, got there a bit early so parked up. Started up after an hour, but engine was running very roughly - kept cutting out completely at traffic lights. Restarted OK, but then cut out again at the next set of lights. Wouldn't idle, almost as if suffering fuel starvation. Gauge did not indicate overheating and the radiator is fully topped up.
Drove home (85 miles all motorway). Once home fault had completely disappeared, idling perfectly.
Car has done this before. Always disappears after a fairly lengthy journey at 60+ mph. Anybody shed any light?
I think I have found the problem. Engine was in fact overheating, but not really showing on the guage. Thermostat was stuck slightly open and although I didn't realise it (not using the heater in the hot weather) the hose to the heater was blocked. So overall cooling not really working very well. It seems that maybe the heat build up under the bonnet when parked up after a longish run was vapourising the fuel at some point. Restart OK but wouldn't run. Until a long cool run. All fixed now, new thermo, unblocked heater, no build up of heat under bonnet.