Mate
You may have wondered off course a little coming to this forum.

Most guys on here are turbine jet flyers.

However, as an ex ducted fan pilot I suggest you contact Bob Violett Models or go to their website as the BVM mixture control that Bob offered for ducted fan was fantastic and may still be available.
If you don't come right, shoot me a PM and I'll see if I still have one somewhere for you.
Cheers
Springbok Flyer