I'm having trouble regulating my large BGE for low and slow cooks. Say my target is 250. I light the grill, let the coals get heated up, add smoking wood and plate setter and close the lid. I have the top and bottom vents completely open until I get within 25 degrees or so, then I close everything off to just a crack and let it come up the rest of the way slowly. Once I put on the meat, I'm good for the first hour or so, and then it starts to climb.

Last butt I did, the temperature got up to around 350, and that's with everything closed off to just a tiny crack. I'm using the Smokeware aftermarket cap because I rad on here that it does a better job of regulating temperature. My butts are coming off ok, but by ribs seem like they are getting too hot too fast. Trying to do some of both for Labor Day, but it really bothers me that I can't do the like the folks do in the videos on YouTube.

I don't want to get one of the BBQ Guru set ups because they are pricey and mainly because it seems like cheating. Whats your method?

How old is your egg? I know when mine was new it was tougher to keep at low temps, but now it will hold at 225 all day with the top and bottom cracked open

If your temp is climbing with just a tiny crack in the bottom vent, then air must be getting in somewhere. Is your gasket in good shape? Is the top and bottom aligned properly? You can do the dollar bill test by placing a dollar on the gasket and closing the lid. You should not be able to pull the dollar out. Check the entire gasket this way, you may find a section that's not getting a good seal.

Bbq guru

Yep

also tip I was told that has always worked for me is that its easier to stop it coming down, than going up.

i.e. if you want 300, get it up to 350 and stop it bringing it back down.

^^^ THIS ^^^

I normally get mine to within 50 degrees of desired cooking temp and lock it down. I can normally hold a 50 degree range for at least 8 hrs without doing anything. It is definitely an art and I'm certain it is different strokes for different folks. But you will learn what works best for you... just go with it!

Your gasket more than likely needs replacing. when mine wore out I couldn't get it below 300 no matter what.

New gasket and problem solved. Can hold 250-260 as long as I need to.

what method are you using for the coals and lighting?

Are you using too much coal? Maybe getting to much fire inside.
I've learned it doesn't take much to cook on. Nothing like a regular grill.

I use the wax cubes to light the egg. I gave up using the chimney started after the first couple of cooks. I have filled up the firebox like BGE recommends. I got the grill a couple of weeks before the Forth of July, but have used it a lot. May just be a learning curve.

There is definitely a learning curve. My only other guess is that you are starting with too big of a fire. It's easier to slowly increase the temperature than it is to cool off a grill that got too hot. For a low and slow cook, you want to start a small fire, not have lots of charcoal burning at the beginning. You'll get it. Most folks use their own strategy that they've developed through trial and error.

I got the smokeware cap this summer and I am having trouble on the low and slow cooks. Had better luck with the Dailey wheel.

Also try using vey large chunks of charcoal, it only takes a few of them.

I solved the problem with a DigiQ dx2. Greatest thing since sliced bread.

when trying to cook low and slow try this. Just light the middle of your coals and put the plate setter in and shut the lid with the bottom vent wide open and the daisy wheel maybe have the petals halfway open. If the coals stop putting off smoke and you want the temp a little higher just open the petals a little more, if you want it lower close them a little more. If that doesn't get it where you want it then you can close the bottom vent just a little. When you have a stable temp where you want it, put your soaked (never dry) wood chunks in and throw the drip pan, grate and meat on. When you put that meat on, the temp will drop dramatically but don't start fidgeting with vents, just leave them were they were when you were at your desired temp. The meat will heat up and won't be acting like an ice cube in your egg and everything will come back to normal. What's believe is happening when you leave the top and bottom vent all the way open when lighting is your fire is getting way too big, then you close the grill and put meat on and it appears for a little while that all is well until that meat warms up a little and quits cooling the egg and you realize that you have created a grilling fire.
I do 90 percent of my cooking with the bottom vent all the way open and do all temp controlling with the top vent. You don't need to be a cheater and get a $300 fan hooked to a thermometer, just learn how to control temp. It's all about airflow

Sorry, didn't see you were using a smokeware cap. Try bottom vent completely open and 1/8" to 1/4" open on the cap ("=inch)