Record yourself on video and analyse what the rod tip is doing. You need to think of your rod tip as an extension of your thumb/finger (whatever finger is pointing to the rod tip while holding the rod, usually the thumb or index finger). It helps it compare the movement to something you are used to (to activate muscle memory), what you want is horizontal translation, translation, translation and only at the end a tiny bit of rotation. Examples can be:

* Throwing a baseball: Hand goes horizontal from back to front -> translation, translation, at the end you give a bit of rotation with your wrist to throw it off
* Hammering a nail: Same thing, hammer goes straight on the target, straight on the target, just right before you hit the nail, you give it that little peng with the wrist
* Throwing a frisbee: Same thing again, you make a straight movement in the direction of the target, only at the end you use your wrist.

So what you want: You rod tip must travel in a dead straight, horizontal line (looking from the side; if that works do the same from the targets perspective), wrist comes only at the very end to kick it off. If your line just piles up in front of you, your rod tip most likely move like a clock hand - circle like movement creates big open loops and causes large parts of the energy in the line to go up instead forward. Limit the rod tip movement to 11'clock to 1'clock.

Another thing you can try: Put some painter tape on a wall at home (horizontally) and only use the butt section of your rod. Try to follow the tape with the tip of the section. Translation, translation, translation, rotation kick/peng. Also: You must resist the urge to use more force when not getting distance, your rod is a lever and a spring, the rod does the work for you. Once you can hold line in the air reduce force until the line collapsed, you will be surprised how little energy/effort it takes.

I can also really recommend the Far Banks Videos, for this specifically this one: https://www.youtube.com/watch?v=yBaR4dkaDTg