I have a 1998 Jaguar XJR. Recently, I cleaned one specific fuel injector due to a suspected misfire. Here's what I did:
1. Removed the injector.
2. Sprayed carburetor cleaner through all the small ports of the injector.
3. Sprayed carb cleaner directly into the fuel injector hole to clear out any debris.
4. Reinstalled the injector and started the car.

After this process, the car initially wouldn't start I think I might have flooded the fuel system on that rail . I managed to start it by flooring the accelerator pedal. Which apparently cuts out the fuel injector momentarily after research. but now it runs rough and is in engine failsafe mode. The car also threw a code P1224 (Throttle Position Sensor).

I also disconnected the battery for a few minutes reconnect the batteries still the same code and running rough. Engine light came on as well P1224
The car was running fine before this maintenance. I suspect the flooding might have caused the issue or there might be a problem with the injector after cleaning it.

 

Did you investigate ALL the Possible Causes listed in the DTC guide?