Why does Dongfeng Shen Feng a30 shake a little when driving in rainy days, and the throttle can't be added?

First of all, I suspect that the throttle is dirty. Secondly, when it rains, the oxygen content is low. In addition, the temperature is high and the oxygen content is lower after hot car. A dirty throttle will lead to the reduction of idle air intake and the body or idle jitter. If my answer is helpful to you, please set it as the best answer, thank you!