I have a volvo 4cylinder AQ125.It does not overheat until I open it up at high throttle.When idling it is fine.I changed the thermostat and inpeller.I flushed the heat exchanger out and made sure all water supplys had good flow.Compression is at 140 to 145 on all cylinders.Only thing I have not changed out is the fresh water pump.I will check it but could it be anything else?