A little help...

I just got my car, a '95 SC2 5 speed manual transmission, back after I had to get the engine replaced. It runs excellent, but my engine temperature gauge won't move or it will move very little bit, it stays down almost on cold. The thing that confuses me is that I still get heat when I put the heater on so it doesn't seem like the engine isn't hot or anything. Does anyone have any idea what it is? Is it just a bad connection in the gauge or what? I had to replace the engine coolant sensor last summer and I don't think that's the problem because it runs perfectly fine and when my sensor blew over summer it would rev high and then shut off. If anyone can help, Thanks in advance!

check the temperature sensors. these need to be changed every once in a while in older saturns.