The rules say that the investigator may on take on movement while stunned, but can he perform a run action?

In my point of view, he/she chouldn't since he/she's stunned, but there isn't nothing, that I could find, in the rules that say he can't.

Couldn't find anywhere some precision for this matter.

Can someone bring some light?

Thanks in advance.

Yes, s/he can run. "Run" means to use your action to move one more space. A stunned investigator moves one fewer space on his/her turn, so s/he moves 2 spaces with a Run action, and 1 space with another action.

well, they may only take 1 move action (1 space)

they can then use their run action to move to an adjacent space.

So a stunned investigator can move 2 spaces in total, at the cost of one movement and one action.