fiat scudo temperature problems??

Hi, i have a 2006 Fiat scudo 2.0jtd. Yesterday whilst sitting with the engine running the temp gauge kept flickering up and down irratically then went up fast which put the light on and the STOP light in the centre of the clocks. After further investigation it was not overheating but the top hose was cold and the bottom hose only warm?? The gauge goes up and down now with a mind of its own and when it puts the lights up it now sends it in to LIMP mode? Has anyone experienced this??? Thanks.