Riding Mower Won't Run With the Choke Off?

I have an MTD riding mower, 18hp twin power. I have a carburetor issue, if I choke the carb and cover the little hole with my finger, the engine starts right up. If I remove my finger, it will die. I run the rider with choke pulled out fully. I am unable to utilize the throttle control or it will die. If I push in the choke just a little it will die, does anyone have an answer to my dilemma?

By Dano77 from Buckner, MO