In addition to good advice from others, I'd start by taking the
mechanical vario off the system. The 302 is very fussy about sharing
lines with other instruments, and flow-based varios in particular. Get
the 302 working right on its own, then see if you can add the other
one back without making the 302 work worse. Also leak check the pitot
and static too. I had weird 302 problems twice that came down to leaks
in the ASI and ASI tubing.

John Cochrane