First thing to check is the ECU body rot.
ECU is under the plastic cover on the passenger side of the engine bay, right under the passenger windshield wiper.
Pull the plastic carefully, do not break it, remove the ECU and check if its aluminium body has rotten.
You may want to clean it, apply silicon heatsink compound onto the body and steel bracket, re-install and spray with Rust-check.
If it is badly rotten with the through holes, you will need to replace the ECU.