Battery change

Why won’t my car idle after changing the battery on my toyota camry 2002

The memory may have been lost in the ECU due to the power being removed too long. Check the Owner’s manual and see if there is a procedure to allow the ECU to relearned the idle for the engine.

The throttle body and idle air control valve could be very dirty and the computer had compensated for it over time.
Now the computer is reset and the default idle setting is too slow.

I have never seen that before. Is everything hooked back up, including all the ducting associated with the air intake system? If so, you might try spraying some sensor safe cleaner on the MAF and TPS sensors. I’d look hard for something unhooked, a vaccuum line, a piece of duct work, a plug, etc.