Fault codes are better cleared with the scanner.
Clearing them will also clear any learned values.
If there is still a mixture problem, the engine will relearn immediately when warm.

Faulty speed sensor cannot cause this problem.

If the MIL goes out, then the fault codes are no longer active. The MIL only goes on when they were active codes (in service 3), but they can be duplicated as pending codes (in service 7). Service 3 codes are kept for at least 40 more engine starts.