They look great! I haven't used my mini for ribs yet, but I'm going to!
I see you foiled them, did you use the 3-2-1 method?
As far as the temp issues goes: Did you wait for the coals to get up to temp before you put the ribs on? I did a rib roast on the mini last night and had the same trouble keeping the temp up at the 350 mark once I put the meat on. I ended up removing the ashcan from the vent and that did the trick.