98 z23 3.8 oil pump problem

i have a 1998 montecarlo z34 3.8 and the oil is not getting up in my valve covers or moving right. also there is a small round blue sensor plug that i dont know where it goes, possiblly to the oil pump?

Welcome to AF, no tube or sensor here, get the pressure checked using a gage on the oil sending switch to get the actual OP reading first.