(IMG:
style_emoticons/default/00000732.gif) daygobeh,
First, you have a 20-year old car! Is this the original oil pump? Luckily, the oil pump is easy to replace. First get your oil pressure tested at idle (750 rpm) and at 2000 rpm. Of course, your pressure will go up at higher rpm. But if your idle oil pressure is less than 40 psi (from memory, you should be at 40-60 psi), you will need your oil pump replaced.
The thermostat had nothing to do with this problem. Since you are is Sasketchewan, are you running a 5W 20 oil as you might at -40 degrees Celsius? You could also go up in viscosity with an oil change. thicker viscosity will create higher oil pressure readings.
Byron