I'll admit I "assumed" something too... based on your original post.
I'm "assuming" that it runs fine at full throttle, nose up and vertical. Correct?
If not, then I agree with the previous person who said definitely check out fuel lines and such.

If it's fine at throttle positions other than idle, and it flies ok... no problem.
You might add a one-way checkvalve inline on the pressure side... to hold a bit more pressure,
but I can't think of much else, off the top of my head, that might be of any assistance.