Volvo Repair: 89 Volvo 240, clutch fan, gas gauge

Question
The car was overheating - have replaced the thermostat, water pump, timing belt.  The car is still running hot - mechanic says because the transmission is not downshifting properly (at 40 mph).  I'm totally confused and do not trust the mechanic anymore - put too much money into it and still isn't running properly.

Thanks so much

Answer
Joanne, that is the most ridulous thing I have heard yet.  2 questions.  Did he check to see if there was a bunch of junk blocking the radiator in the front?  Is the water pump clutch fan working?  It may also be giving a false reading.  the 89 has a computer board in the instrument cluster that controls the gas gauge and the temp gauge.  It goes bad from time to time.  If he was a good mechanic, he would have checked the above things.  Roger