Is that one you have? Have not seen one like that before. Grill and stackable smoker in one unit. Interesting.
I bought the one at lowes that is very similar to the Austin XL, the 1100 pro series. I also had very uneven temps across the grill, did some digging online and it seems like everyone(even pit boss themselves) say to remove the diffuser plate that covers the burn pot for more even temps. I can attest to removing that keeps more even heat across the grill. Of course this is all void if the above is the grill you bought.
No, that is the new one they came out this year. Jeff from smoking meet.com had a review on youtube and liked it. I started seeing a bunch of reviews saying parts were not lining up when put together so you got a lot of heat loss. Saw several that stated the doors on the stackable part wouldn't even close all the way. After started seeing all the bad reviews I noticed the grill was removed from walmarts site. I see it is back now though only available in store. I'm wondering if they had quality issues and they pulled them to get that fixed before selling again.
I have the 820 model. Got it from Lowes also on clearance. The diffuser plate is something they added to your model. Mine and the Austin XL do not have a diffuser. I just have the drain plate.