SNIP// Remember, though, adding throttle means you've just untrimmed your plane and it will not fly straight and level at the new RPM (speed) and another trim adjustment may be necessary. //SNIP
I am SOO glad to see this posted by someone with experience, I just always have assumed it was normal to have to retrim my elevator when I change throttle speeds for any length of time. (Actually I trim it for an average speed for how i feel like flying and then leave it alone unless I want to slow down or speed up)
Thanks CGR!!