Alyce,
I had exactly the same problem you mention with the purple Big Foot. It rubs on the needlebar and hangs up then it skips stitches. I believe that when it "wears in" that it would likely stop skipping, but really who wants to do that?
If I change absolutely nothing with the machine other than the foot, there's no skipping. In my case it's not a timing issue for sure and I would strongly advise you to rule out absolutely everything before taking on the timing, and check the timing before just retiming it. I have only had to time 6 machines in total in the years I've been working on machines. Two came to me untimed from someone experimenting, one was legitimately wrong for no apparent reason, one had broken hook gears - a Singer Diana, one had been thrown from an embroidery pattern sized too small, and one had a broken hook. None of those were 301s though, and the 3 301s I've had have all been timed fine and FMQd great if they didn't have the purple big foot on them.
I also don't love the foot with the yellow grid. For some reason, my eyes feel like I can't see what I'm quilting, which I know makes no sense, since it's clear plastic. I like the one that Leah Day sells for low shank machines (4021) as well as the metal equivalent 4021-L), so not relevant here.
For the 301, I use the original Singer foot 161596 which is difficult to find now.