We didn't get there 4A91 in the US, however it's a fairly safe assumption that similar Mitsubishi service methods would apply across the board@michaelluscher
It's a 2010 Lancer with the 1.5L 4A91 engine. If you have access please check if it indeed has molybdenum. As for the relearn is the scan toll absolutely necessary or will the ECU adapt to new reality? That's what a Mitsubishi electrician had told me in the past that letting the car idle for a while will make it relearn whatever is needed for the throttle to operate as designed.
You could try disconnecting the battery and letting it idle, that might be enough

Good luck
