Are you running them both of the same TE line? If you split the line
too close to the varios, they will interfere with each other causing
"jumpiness"

Yes they use the same TE line, each has about 4" of lead from the "T" split.
I have no idea if that's "too close" to the varios...

Also, if you are using electronic compensation for the 302, have you
tried adjusting this?

I have the TE line connected to the 302, so I guess the answer to this
question is no, I'm not using electronic compensationl. The parameter on
page 9 (or is it 10?) for this is set to 0.

This morning I tweaked some settings using the PC software, and subsequently
the vario function worked properly, including reading zero on bootup.
However the speed to fly function is still nonfunctional. It wants me to
fly, like, zero knots or something. I triple and quadruple checked all the
settings so I'm pretty much stumped on this one.

2NO