Vertical dives should be done under full power, too. The max power setting for vertical performance is a no compromise thing with me, a tach helps, tune for max, then back off a few hundred. If your engine is loading up at part throttle, then your tank could be too high with relation to the engine, or the airbleed is insufficient. Muffler pressure usually irons out inconsistent, attitude sensitive running on glow engines. Trying to set up a clunk with a one or 2 oz DUBRO tank is a waste of time, just run a solid piece of 3/32 brass tubing to the rear, and do all the stunts you want, except for inverted flight that lasts over 15 seconds. If you have a hard landing, you will never have the problem of un kinking the flex line, that has pinched itself off when the clunk flies forward, a real time waster at the field.