Modern Vespa

Recently picked up my first MP3. Usually work on older scooters without fuel injection and ECU's so this bike is throwing me for a loop!

It starts immediately everytime but after a few seconds the idle starts to bounce between 2k-1k rpms and then it dies shortly there after.

It has new spark plugs, new air filter, fresh engine oil, and I just cleaned the injector and the throttle body to try to rule those out. Planning on doing the valve adjustment next just to be sure that's right. Battery is new and tests at 12.6 volts.

A few other details that may or may not be related: the tilt lock currently does not work. Have new parts for that on the way so hope to have that repaired soon. Parking brake light always stays on even when it's not engaged. Rear brake needs to be bleed still but was giving the previous owner a hard time (I have not tried yet) I could see some or those thing effecting the acceleration but would it also cause erratic idle?

Any other suggestions?

Thanks!

Sounds like you have a vacuum leak between the airbox and intake port.

Check all clamps and hoses

The bike should idle steady between 1600-1700 rpm when at full operating temp