oven temperature not correct?

If the new sensor reads properly on an ohm meter for it's thermocouple value to the control, make sure it's grounded to the chassis of the stove on a one wire common return sensor. If the sensor reads right on the meter at the control board, the issue must be in the electronic control assuming the chassis ground is good on the electronic control board.

I know this sounds a bit tedious but there's no way to diagnose it without a model # to look up. Assuming it has a sealed bulb thermostat control to the oven gas valve that works up to temperature on a external oven thermometer, the thermocouple sensor or electronic control are the issue on most ovens with a split manual temp nob / external digital cook top back splash temp readout for the oven.

My workaround when I noticed my temperature was a bit off was to buy an oven thermometer that sits inside. Then I know what the temp really is, despite what it's set at.

They're cheap. Might be a good tool for at least learning if the oven is heating to the correct temperature that you set it no, despite the read-out being wonky. And if that's the case, then just pay attention to the setting, and ignore the read-out.

It seems your control board has failed in this respect. If you've replaced the sensor, checked connections and inspected the overall condition of wiring then the control board is the likely culprit. They're expensive but with some diligence they can be found at discounted prices. Do a search of your model number for parts and obtain the control board part number. Search Google for the part number to find the best price. Used boards are okay if the seller will give a warranty and the cost is low otherwise buy new with a return policy from the seller.

I recently had to replace mine in a Sears oven. Sears wanted $290 for the board but I found a new board online from a parts dealer for $124.

I suggest looking at the owners manual, and if you don't have one for some reason, look online for one