I have the same problem but on Fiat Punto 75sx 1999. please let me know if you slove the problem and will do so if I solve it
Punto head gasket change is quite an easy job to do. It is almost impossible to give step by step instructions on these pages. The best that I could suggest, is for you to get a Haynes manual for the Punto this will show the exact procedure to follow.
If its a 98 60sx mk1 punto then you have to take out the screws at the bottom of the door pockets then use a flat screwdriver to pop it out from the bottom workin your way to the top an lift it round the lever that opens the door then over the locking pin.
asumeung its a single point injection it is located on the throttel bodie next to the injector. if you lift of the air box you will see it on the right hand side of the injector looks like two very small pices of wire soldered together with a blob of glue with a black plastic ring around it. as for multi point injection this is usaly a push fit in to the air box. but please dont tamper with it or you could damage you engine.