Modern Vespa

I had another thread on a bunch of stuff I was doing to my liberty 150. Really the last challenge is harder starting when it's cold and idling BEFORE the engine gets warm. If the engine is really cold, it'll idle rough or just stall until i get a mile running it. Then it's perfect.

I'm zeroing in on the engine temp sensor after getting my hands on the workshop manual. It just makes sense it's running too lean when cold. Scooterwest has them in stock, but they're like $95.

Is there any way to re-calibrate / check them other than just replacing? Or even better confirming I need one before ordering. I saw another post that was suggesting let it idle with no throttle for 15 min to help re-cal it, but I didn't see anything about that in the workshop manual. Not sure if that's real.

Any thoughts would be appreciated!