Hello there;
The temperature gauge on my 2002 Chevy Venture does not seem to be working, the radiator and termostate have been recently replaced. The gauge moves all around the left side and never makes it to the normal temperature level, even after a while of being driving around with an exterior environment temperature around the 90's..! What could be the possible causes/solutions for this?

Check the electrical connection on the sending unit. Remove and clean the connector with abrasive cloth, spray with WD-40, and seat firmly.