I buy my sis-in-law a 150 hr '98 xl1200, ride it for a day and all is well.

The second time she and her hubby take it out they say it cuts off at low rpm's, it won't idle. First time she ran it it was fine. Started dieing only after re-fuel from Marina. I put the new blue Stabil in with her gas from gas can. She wonders if lack of the Stabil for ethanol in this tank could be problem. (She didn't ask if the fuel contained ethanol or not)
If you guys tell me the carbs need to be gone through she's gonna kill me!
What do I need to check?