Originally posted by au_Nightmare
I am sure this is a silly tuning question:
Problem is, I can go full throttle / idle no worries but if I use 40% throttle engine revs, then starts to bog down (flodding) then coughs a bit then stops. Where am I going wrong? 
Pipe is THS pipe on LD3.
(I have a feeling someone is going to say try longer pressure line? hehehe)
This is a midrange tuning issue. Our little nitro motors really are not made to run well with these types of throttle settings (carb design issue). Most of them run quite rough when the low speed needle is just about to completely unseat from the spraybar since this is not really a position used very often in racing.
I am not familiar enough with the STS yet to answer this question fully. Playing with the mid range needle may resolve this issue somewhat, but it may well be an issue related to the design and shape of the end of the low speed needle.