Top Layer is Stringy, Disconnected

Hi,

I am having an issue with the top layers of my print. They come out stringy and disconnected in spots. This is most visible in the areas where the infill buts up against perimeters. I also notice that the perimeters are splitting apart. I can't fix this by increasing the extrusion multiplier, so I don't think this is an under-extrusion issue. The weird part is that, when I print a portion of my part (same height, but cut into a smaller XY dimension) as a test, it comes out fine. It only does this when I am printing the entire part. I'm printing in 3DXTech ASA on a Fusion 3 400S printer. The relevant settings are as follows (in Simplify):

Extrusion Multiplier: 1.05
Layer Height: 0.15
Extrusion Width: Auto
Speed: 2300
Extrusion Temp: 255
Bed Temp: 100 (95 after layer 7)
Fan Speed: 0 (15 after layer 7) (65 for layers less than 13 s)

Any thoughts? Thanks.

Are you sure its not grinding filament?