If it's driving you crazy, I'd say take it out. I have not had good luck with stem plants lately, so I can understand your concern.
The thin-leaf elodea did all right for me, but hornwort and anacharis just failed. Melted all over the place.
Turning down the heat may help, but you need the heat to grow your bacteria, which is probably more important than the plant.
Just an opinion, at any rate, I hope something starts to improve! Messy tanks are frustrating!