It would be easier to comment with an image of the rendered scene. Otherwise we must guess what your problem is.

I think the streaks may be coming from your shadow map size. Do they go it you inscrease it.

I'm not aware of the position of the IBL light mattering unless you have shadows set. I usually set it to 70-80% strength, and put in 1 or 2 infinate/spots for shadow/specular. If I have AO in a light I usually put it in the IBL but reduce the strength to 3 or 4. AO can leave artifacts on some surfaces and I have to alter the bias in the scene settings.  This could also be the cause of your streaks which is why I asked for an image.

As an alternative to putting the AO in the lights you can also put it in the actual materials.