Why I am having thick clear mucus in my esophagus and that its difficult for me to swallow feeling like my throat is open that doest close anymore.

See a doctor. Get examined. This may be due to acid reflux, or to post-nasal discharge or to something more severe. It should be looked at by somebody professional and not taken lightly. Good luck.
Open throat. Allergy, inflammation, acid reflux, copd, infection & some medications cause thick mucous. Your problem is difficulty in swallowing. For this problem, video fluoroscopy modified barium swallow study and egd by gastroenterologist could be helpful. See your doctor. Good luck.