Inconsistent extrusion with Cura

[gwatson1990 1]

I've recently been printing with PETG and I've been having what I think to be some extrusion issues caused by Cura lately. On my first few test cubes the lines were so thin that I could still see the "Ender 3" on my Ender 3 print bed. This is not reflective of the print settings however, which are:

 

Nozzle Temp: 240c

Bed Temp: 80c

0.2mm Layer Height and 0.4mm Line width

Initial Layer width: 150% (0.6mm)

Normal layer extrusion multiplier: .97

Initial layer extrusion multiplier: 1.00

Travel Speed: 150mm/s

Print Speed: 40mm/s

Retraction: 5mm @ 20mm/s

No cooling fan

Coasting: Enabled

Combing: Not in skin

No Z-Offset

 

It was suggested that I should lower my speed from 40mm/s to 20mm/s (Outer wall speed: 10mm/s!) so, I did and the next cube came out with much better layer adhesion and the line width I was expecting given the settings.  I then decided to print this from thingiverse:

 

  https://www.thingiverse.com/thing:2856991 

 

 I used the same settings and when it started to print I noticed the line width was back to being too thin again just like before. The only thing that I could do to get the desired width back was to up my initial layer extrusion from 100 to 150 which from what I've seen is way higher than the norm for PETG settings. So Iet it print while I was sleeping and the next morning the finished print had a lot of fine stringing between objects (objects were fully printed though) and when I removed them from the plate everything above the first layer essentially crumbled under any kind of pressure. I had a similar issue with PLA during a bigger print and had to up the extrusion rate to an abnormal level a few days earlier but the layer adhesion was still good. I don't know what the deal is now, I'm ruling out any hardware issues because I've got no clicking or shavings from my extruder, the filament sits on a roller inside a dry-box, there is not cracking and popping from water in the filament out of the hot-end, and I've verified my temperatures with a thermistor on my volt meter. Anybody have any ideas or ran into this kind of problem before?