anybody who tells you she/he has never had that problem has never sewn a single stitch. lol

That's for sure!

When you get close to the end of a seam to put your left finger on the edge of the foot and that will stop the seam from getting wider or narrower. I don't have to stop to pick up or find a tool to use. It's automatic for me to put my finger on the foot when I come to the end of a seam as I've been doing it since ninth grade home ec class.

Oh Patrice, that is funny but so true!

This is what I do. I use a seam guide and I just slow down and make sure the fabric stays next to the seam guide

Yep, finger on the foot works every time.

I just watch as I get close to the end of seam.

This is what leaders and enders are for. You don't get that wiggle if you are chain piecing, so leaders are a piece of fabric you put before the piece you want to sew, and enders are for after. Some quilting guru (Bonnie H maybe?) keeps 2" squares next to her machine, and she just grabs 2, a light and a dark, slaps them together, and uses them before or after whatever she is sewing. Cut them off, toss ina basket, and when you have a big pile of them, make them into something scrappy. 4 patch, 9 patch, whatever. You can also cut them down, if needed for whatever.

Some people keep a piece of scrap fabric and just sew over it till it's so full of thread its unusable, throw it away, and start on another.

The other thing I have found is that if I am sewing with a straight stitch throat plate (the kind with just a single hole instead of a wide slot for zig zagging) I have fewer problems with that as well as the fabric getting stuck in the slot.

I find this, too. Hang on! And I have several stilettos. A chopstick works, as does any dowel. Cut the length you want, put it into the pencil sharpener and gently grind it down to the desired sharpness. You don't want it completely sharp. Leave the end just a little rounded.