no movement when tempreture is high.

Is there a Check Engine/Service Engine Soon light on? If so that would indicate where the problem is likely to be. In any case it could be a lot of things causing this and without being able to drive the car and do basic tests it's to hard just to guess. Start with the basics, has the engine been tuned up, you know the spark plugs are good, the compression is even and there are no vacuum leaks. Even if the Check/Service engine light is not on a professional grade scantool can read key engine sensor data and see what is out of range or what the potential problems are without having to do intrusive testing at each sensor. Volvos are a little unique. Find a repair shop knowledgeable in Volvos and European cars not just a back street shop or chain store repair franchise unless they have knowledge on repairing modern Volvos.