Those are some major weaknesses. The main thing you can do to overcome them is to practice.
Get a partner who is interested in improving his game as much as you are.
Begin rallying. Do not let yorself be tempted to wallop the ball. Do not try to hit winners.
The idea will be to keep the ball in play as long as you can-- hitting just medium speed balls.
Rather than concentrating on power, concentrate on getting to the ball and setting up in good form and hitting through the ball smoothly and cleanly.
Hit like a hundred balls forehand to forehand down the middle, then the same with backhands.
Then hit crosscourts, forehand and backhand.
Then hit back and fort first to the forehand then the backhand-- not looking for winners-- just for practice.
Eventually, with all that hitting and concentrating on form rather than pounding winners, your strokes will improve. As a side effect you will also be working on your stamina and footwork.