Do you have an electronic water pump? For whatever reason my elec wp wasn't coming on. The wiring was a bad connection so sometimes it would lose contact. I had to hook up a relay wire connected to my fan switch but if yours is the stock wp that's another problem. Have you checked your fans to see if they are both coming on? In the past I had to hook up a fan switch relay to turn on the cooling fan because only one was coming on. If the fans are coming on and still overheating changing the tstat if you haven't already is a good idea. Most of all make sure your coolant is full. Sometimes air bubbles form in there. So take the cap off let the car run while you fill it. Hopefully one of those work out.
hey Gabec007 i was reading ur post about ur car overheating, and i am going thru the same exact thing for the last week. im driving to work and my car temp gauge goes up and goes down when i give it gas. The last couple of days that hasnt been working tho, i have to pull over and wait for it to cool down. Did u get ur problem fixed, and if so, how?