AZBBQ - something definitely out of sorts here. An hour to get to 250 doesn't sound right. I only have three 3/4" nipples & I will be at 200 & closing one nipple in less than 10 minutes. I can run 250-275 with a ball valve half open on just one nipple.
I would say your basket needs to be raised a little more, but that would just to keep the ash buildup from choking the fire late in a cook.
If your fire spiked with the lid open then quickly dropped after closing, I'm thinking you are not getting enough air drawing thru. Do you have a 2" bung hole open in the lid? Anything smaller probably will not draw enough.
Jim Sewell -- GBA Master Judge, Contest Rep & GBA Webmaster