Greetings & Salutations Dave!!!
Could be many things. Most likely some sort of vacuum-leak:
1. check rubber manifolds between throttle-body and head
2. check rubber hose between manifold and MAP sensor
3. measure MAP-sensor voltage-output with key ON/bike OFF
4. measure MAP-sensor voltage-output with key ON/bike idling
5. compare #3 and #4 with values given in manual
Most likely issue with MAP sensor, disconnected or cracked hose is common culprit for these symptoms. Might also be fuel issue:
6. how long was bike sitting before owner ran it recently? If more than 6-months, dump tank and put fresh petrol in with some PEA-based fuel-system cleaner
7. fuel pump? Follow test in manual to measure fuel-pump flow volume and pressure.
8. fuel filter? Might be implicated in #7 if flow is below limits.
9. fuel injectors clogged? There's way to measure their flow. Might be easier to just send them to
https://mrinjector.us for cleaning with before& after flow-testing