Hey thanks for the reply. It wasn't a proper load as i only wanted to test temp adjustments using the vents after the foil gasket. What led me to take this route was 280+ degrees with all the vents shut.. and i think it kind of worked. I wasn't meant to cook any ribs at first but.. hey, ho :)
I usually drop 15-20 briquettes over an almost full ring of either lump, or lump/briq mix. I used to spread them out but now i try to keep them covering about half the diameter of the ring as the fire was spreading out too fast, too early.
Interesting that cracking the lid fuels the fire, i guess it creates a draft or something.. will have to try that out on the next cook. Your 65 degree drop was huge btw!