My character has only clothes on him, but the game says he has 80 in weight on him, is this a bug? Am I able to clean it with some program?

the problem may be because of a few things.

1)you may only be WEARING shirt and trousers, but you may also be carrying 70-odd weight in misc items.

2)80 may be your TOTAL carrying weight, and not what ou are carrying at that time

3)you may have been hit with a burdening spell

This kind of thing happens when you Have items from a mod in your inventory when you take off the mod. I don't know the solution to it, sorry.

EDIT: what you can do is make an item in the CS which has feather 80 points, constant effect. Like a ring or a shirt or something, equip it and that will solve the issue.