I'm in need of a frequency valve please if anyone has one available for sale.
You've probably checked this out already, but
just a quick tip before condemning the frequency valve, remove the white electrical connector plug on the frequency valve and check to see if one of the pins has 12v to it with the engine running. If it doesn't, it could be that there is a fault with the lambda relay being the incorrect type (especially so if just replaced) or that there is a connection issue at the "church window" electrical connection under the coil cover or the lambda/fuel computer itself not powering up (or missing earth from one of the two earth connections at the computer)
Good luck either way