Here's a simple and cheap way to tell. Go buy some canned biscuits from your local grocery store. Preheat your oven for 30 minutes to the appropriate temperature, and set a timer to the middle of the time range given on the can. When the timer goes off, check the biscuits. If they're still raw, your oven is running cool. If they're overdone, your oven is running hot. If some are raw and some are done, you've got a hot or cool spot in your oven. The byproduct is that if your oven is close to be calibrated correctly, you have biscuits.
The reason this works is that the recipe for those biscuits has been tested thousands of times, and they've been carefully calibrated to work every single time. FWIW, this tip came out of the Bouchon Bakery cookbook.
Also, how dirty is your oven? A clean oven cooks more evenly than a dirty one.