Usually, people would just say 我要吃飯 or 我想吃飯, but I suppose saying you want to do something also works. For example: 我好餓喔！我覺得我該去吃飯了。 (I'm hungry! I think I should go eat) 時間太晚了。我想我該去睡了。 (It is very late. I think I should go sleep)

you are trying to use English grammar in Chinese language to express what you want Chinese people say "I hungried = 我 饿了"

Xiǎng : means think, want. It'll fit the blank. However, Mandarin speakers never speak this way. We usually say: Wo Yao Qu Chifan Le. You Ren YiQi Ma? (I am going to have some food. Is there anyone who wants to go together?) Wo Kuai E Si Le. Wo Yao Qu Chi Fan! (I am starving to die. I want to have some food!) Ni YiHui You Shi Ma? Wo Yao Qu ChiFan. (What are you going to do next? I am going to have some food.)

I think I should go to eat something. Wo xiang wo ying gai yao qu chi fan le. 我 想 我 应 该 要 去 吃 饭 了。