First, you have to make sure your controls are set-up right.
Goto the clipboard, and click options/map controllers. In the top "drop down" box select the controller you have your throttle on...some are on a stick, others are independent. Select the axis that your using "Z" I believe, and "check" the "advanced" box. This will swing out another page to give you the sliders and dead band adjustments. Moving the throttle thru its full range of motion here will show you a line scrolling up and down the blue box. With full throttle the line should go all the way to the top. If it doesn't, recalibrat it now.
Next, test it in flight. All planes take a certain amount of time to get up to speed. Some are quicker off the line than others. Of your list of planes you tried most, none are real screamers off the deck. These are not modern jets, nor are they x-wing fighters, you have to give them time to biuld speed. Take off from a base near the shore, get your wheels up (hit G for gear), and turn carefully toward the sea. Hit "x" for level auto pilot and give the plane a few MINUTES to build speed. If your throttle is working right, the plane should slowly build speed. Good manuvering speed could take 5-8 minutes depending on which plane your flying.
There is an old fight pilots saying that "Alt is life" The meaning behind it is you have "stored energy" when you have alt. Nosing over will turn that stored energy to speed quickly giving you that manuvering speed fast. Alot of people you are seeing blow by you have most likely done that, dove from some alt to build speed. Manuvering burns off this speed so be carefull how you use it as it takes time to re-build it.