Everyone calm down [not everyone], worrying too much is not healty at all for the person Jacktrade or the kittens.
Now: it’s hard watching over 1 kitten, let alone two mama cats and their kittens. I would suggest that instead of keeping the kittens you give them up to a no kill rescue shelter, they are more equipped with watching so many kittens. Is Mufasa a first time mother? If so she is probably trying to get away from them because she is so either unprepared or not ready or just scared.
I know you have stated you have no mone y to get formula, may I ask how you got a litter pan for mama, food for her? I assume you have these only because they are essential for a cat living, at least the food is. In my honest opinion, you either need to give up one or both mama cats and their kittens because this appears to be too much to handle, this is second time that Mufasa has gotten out, you need to watch her more carefully if she is in a garage. What is the temperature like where you live? Is your garage ventilated with the rest of your house? Or does it have no AC/heat?
I do applaud you for taking in both cats and their kittens but it’s hard work with just one mom and kittens. No one would blame you if you gave up both for fostering. It’s a hard job and while you’ve been doing fine for three weeks, it may be time to consider that a possibility.
Julia: There is no need to be rude, I’m sorry but formula is expensive for one kitten, it can get even higher for 4-6 kittens, however many Mufasa had. I realize you are new, but people come here for help, I’m sure Jacktrades is feeling bad enough.