thili

Hi All I live in Malta, and I have a Fiesta RS turbo engine on my Escort Mk4 ..owned for 2years and a half now, and from one month ago its been overheating alot over 100degrees after a very small trip and the engine starts like cutting and also switches off and if i try to start it, it will start like cuttiong and turns back off. now last week when i tried it I also noticed that it wasn't as powerful as before after some time after I go for a small ride I've done many things to solve the problem..like changing the thermostat, see if there is any air in the engine..it should have any, also checked if it is the gasket but almost 4 mechanics told me that it is not the gasket. now I took it to another mechanic and told him everything I done and told me that the only thing left is the Radiator, it is either blocked and it is also small for the engine since it is of a 1.1 engine radiator, but I never had trouble witth it before, could this be the problem? that the radiator is small and blocked? what else could it be if it is not the radiator? ... btw in malta the temperature extremly hot above 34degrees celcius.