Can anyone tell me if this is a theft device issue with my mustang or something else?

I have a 2002 ford mustang and I've never had this issue happen before. Just recently my car has started idling really low at stops and in park but also when I first start the car, the theft light comes on for a few seconds then goes away but during those few seconds, the gas gauge and rpm gauge are not reading until after the theft light goes off then they read normally. Is this a sign of a theft device flaw? Or something else?

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