Uh, I hope that’s total and not “per egg”.
Agreed. The recipe I use is from Joy of Baking and has 3C oatmeal.
Also, are you chilling the dough before baking? That may help.
Could you be using quick cooking oats instead of regular? I don’t know that this is the culprit, but it could affect the outcome.
Before I write this off to “I guess I measured wrong” let me ask one more thing. I’ve made these last two batches with my shiny new Kitchen-Aid Professional 5 Plus series mixer, having replaced my 30+ year old, harvest gold Sunbeam stand mixer. Is there such a thing as over-mixing or something?
As noted in the notes on my recipe, you want to cream the butter and sugar, etc., but the rest should only be mixed until the dry ingredients are incorporated. I doubt that it has anything to do with cookie puddles, but it makes for something less dense. I find that I need to leave the cookies on the baking sheet for a couple of minutes or they’ll fall apart. Maybe try using unsalted butter instead of margarine?
Maybe, but overmixing would more likely result in tough, chewy cookies because of the gluten development. However, some googling suggests that if the butter (or margarine) is too warm, they might spread too much; maybe your new mixer is warming things up too much? As another poster suggested, try refrigerating the dough briefly before baking (maybe even put on a cookie sheet, and refrigerate the cookie sheet with dough balls).
Is the oven fully up to temperature when you put the cookies in? I believe there’s sort of a race between the fat melting and the flour/oat/egg solidifying, that would be thrown off by the wrong temperature (or the dough being too warm).
Are you using different cookie sheets?
Your recipe is the truth. Cookied crack. I have to make more this weekend, but I needed to thank you. It’s just…so good.
I thought of some things that may be an issue:
How old is your baking powder? Mix a little with some water, and if it doesn’t bubble, throw it away and buy new.
How old is your brown sugar? I was having trouble with my chocolate chip cookies having an unpleasant sugary crunch. I replaced my brown sugar after trying to rehydrate the old stuff (not THAT old, really!) unsuccessfully. Problem solved!
Even though your Imperial says it’s good for baking, get some real margarine. It will say “margarine” on the label; you’ll notice most stick spreads don’t because they have too much water added and not enough fat to be legally called margarine. I’ve used Fleishman’s and Land 'O Lakes margarines with excellent results. Or use real butter. 
Made a batch yesterday, carefully measuring the ingredients, preheating the oven, chilling the dough – and mixing everything by hand. They didn’t hold together as well as I would’ve liked, but at least they were solid and not puddly.
Thanks everyone.
I should add that I don’t usually make oatmeal raisin cookies and when I wanted to try it out I used the Quaker recipe. They were terrible, but I think I over-mixed them. Then I used Chefguy’s recipe and they were perfect.
eta: I just saw your update. I think it’s time bake some cookies.
Trust your instincts. If the dough seems way too wet for what you’re used to in a cookie dough, It probably is. I would make up for it by adding more oatmeal, as suggested.
ETA: oh, yes, and don’t let your fat melt. I’ve never used margarine in a cookie, but with butter. You need to cream it with the sugar (I use cold butter and make sure not to overwork it.) I don’t bother chilling my doughs, usually, but you have to bake it right away.
Well, for starters, you completely ruined perfectly good cookies by including raisins in them, the Devil’s fruit. 
Try using real butter instead of margarine. The margarine may be mostly water + a tiny bit of hydrogenated oil of some manner. This would not help.
I use softened butter for creaming. Refrigeration of the cookie dough would likely help the OP, however. I usually only chill doughs that are mainly butter/sugar, like spritz, to help them retain shape.
I bet that’s your problem if your egg substitute doesn’t have yolks in it- they serve a vital emulsification and thickening role in the cookie dough. You might have done something strange with your KitchenAid like frothed up the egg substitute and then had it do something weird in the oven, and that’s why the cookies didn’t work.
Try it with real eggs and see if that changes anything.
Also, I’m a fan of real butter, or (gasp!) butter-flavored Crisco sticks in cookies.
Oooh - while this deals with chocolate chip vs. oatmeal, Alton Brown’s “Three Chips For Sister Marsha” has a good discussion about the things that make a cookie thin vs thick, and the types of fats to use for each variety.
Chefguy, was the recipe you mentioned here the same one you (or someone) listed a couple years back, where you actually put the dough in the fridge for 24 hours to help hydrate the flour or something?
(on rereading, I see you posted your cookie upthread. I’m clearly remembering something else).
That was the cookie recipe with the chocolate discs, which is really rich and really good. And yes, it recommends refrigerating the dough overnight so that the resulting cookie is crisp on the edges and chewy in the middle.