Oven gets warm but not hot?
This could be a thermostat issue or a burner issue. Most ovens have a top and bottom burner, if one of them is not working, the oven may not reach or stay at the right temperature. You should be able to get a replacement at home stores that sell appliances or order one online. They are fairly easy to replace. You may have to remove a couple of screws but otherwise they pop out and pop in. You can test the burners by turning the oven on bake and a few minutes later open the oven to see if the bottom burner is red, if not it may be burnt out. You can set the oven to broil and after a few minutes, look at the top burner, if it's not red it's likely burnt out. If both burners seem to be working, it is likely a thermostat issue. I haven't replaced one of them before, but you should be able to find instructions on youtube to determine if it is something you are comfortable replacing on your on.