Lindsay Lohan -- Coachella, Here I Come ... But I'm NOT Partying!

Lindsay Lohan loves temptation -- she is on a plane to Coachella right now ... and TMZ has learned she is telling her friends she will 100% NOT fall off the wagon.

According to our sources, Lindsay is aware that going to the festival -- famous for great music and drugs -- is a risk to her sobriety, but she has been promising people she is going to stay sober.

Lindsay has been a mainstay at the festival (long before it went mainstream) and goes with her siblings every year. She made this same sober promise last year, famously hitting Coachella right before checking into rehab.

"Insanity: doing the same thing over and over again and expecting different results."