I'm a drill sargeant for a reason...

Sometimes I think that I'm a little too hard on my kids. I don't let them decide much. I tell them what to do and when to do it and expect them to listen. I have learned that that is the way to keep order in a large family. Generally they listen pretty well. "W" always has to ask a few completely unrelated questions before he manages to get to what he's supposed to be doing but he still listens pretty well. I've learned to stop his questions and tell him to do what he was told first and then he can talk to me. Otherwise, he'll ask a question, not bother to listen to the answer, and then totally forget what he was supposed to be doing.
Well, today he and I went to his friends' birthday party. I always let them have cake and ice cream at friends' parties because I don't want to take everything away. If they had an allergy it would be a big deal but this isn't that huge - or so I thought.
They had a pinata and when the candy fell out and all the kids started grabbing it he looked over at me and then grabbed a toy to play with. I told him to grab one piece and he could have it. He did well and grabbed a Tootsie Roll. He ate that and then it was time for cake. I had her give him a piece that just had the white frosting on it and not the red and blue that the decorations were made of. The cake was a marble cake and then Neapolitan ice cream.
Shortly after that I notice his behaviors coming back. He started stuttering again and he hasn't done that since we started eating all natural in January. Since it was a party for 3 brothers ages 5, 3, and 1, there were lots of presents. As they were opening them he was grabbing them and running over and yelling over the crowd to the boys' Mother "LOOK at what he got - a basketball, guitar, etc." When the guitar was opened he just grabbed it and took it away from the little boy. I told him to give it back and sit down. As more presents were opening I noticed that his shaking came back. You could see that he was having a hard time controlling his hands and not helping or touching everything.
After the presents were done we went back out in the back yard. I told him to give his friend a hug and that we had to get home now. He gave his friend a hug and we walked into the house (walkout basement). I stopped for a minute to thank the Mother for having us and to chat for a moment. Then I went up the stairs and he was nowhere to be found. I walked over and looked out the patio door to see if he had gone upstairs and back outside and he wasn't there. So I went out the front door and there he was walking back up the driveway. I asked him where he had been and he said that he had went to the van to get in and it was locked so he came back.
Our van was across the street, a half block away!!!!! So I asked him if he looked for cars and he said he forgot. I almost died. I gave him a lecture but tried to control my anger because I knew this probably wasn't something that he would've done if he hadn't had the food and candy. I know his head was fogging up and I should've given him exact directions - like I usually do.
He'll be 5 in a couple of weeks. I keep thinking that he's getting older and he doesn't need the exact direction of a small child but I need to remember that he does. If left to his own judgement he makes terrible decisions.
I realize that some people might think that this is nothing compared to what their kids would do but you have to know that my kids don't do things like this because they know better. Not because they have learned to listen or are smarter, but because they know they always have to ask to do anything. When we are at home and are getting ready to go somewhere they ask before going out the door. They know they have to ask before doing anything out of the norm.
So anyways, we have another birthday party on Monday and I think that if he eats the food he'll be holding my hand for the rest of the time we are there. I don't want him to feel like a baby but I really don't know how else to keep him safe.