<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I haven't been able to sustain the temp for long periods of time like that. Normally no more than a couple 1-2hrs. Any suggestions? </div></BLOCKQUOTE>
Seems you're definitely doing something wrong. Try this: take a 5lb coffee can, top and bottom removed. Place it in center of charcoal grate. Fill a chimney with briquettes and light 'em. Meanwhile, layer briquettes and your smoking wood onto the charcoal grate around the coffee can. Fill the ring. (Don't worry about filling the charcoal grate. Any leftover coals can be used next time. Just shut down all vents when the meat is taken off at end of smoke.) When coals are lit in chimney, dump them into coffee can and immediately remove the can (using heavy insulated gloves of course). Assemble your WSM, leaving all vents open. (I generally don't use water in the pan, just foil the pan.) When temps are about 25 shy of targeted temps, close all lower vents and put the meat on. Keep an eye on your temp; the meat will cause temps to drop. You'll need to adjust the lower vents over the next 30-60 minutes to stabilize. Always keep top vent 100% open. For an overnight smoke, I generally start this process around 8:30 pm. Meat on by 9:00. Temps settled by 10 pm. Keep and eye on it for an hour "just in case", then off to bed. Set the ET-73 to go off if temp drops too much or spikes. I'm usually up at 5:30am. Temps have dropped a bit, so stir the coals, add a handful, shower and shave and I’m good for a couple more hours to finish the smoke. I hope this helps.