RPMs fluctuating and loss of power

My car has an automatic transmission. Recently I replaced the crank shaft sensor. While they where trying to diagnose the issue with the crank shaft sensor and the ignition lock chip falling outta my key. My car sat for a week. Brake master cylinder being replaced today.

Now I have a different problem. While driving the rpm's fluctuate. It does not happen in idle. Usually, no higher than the 4 mark. It kind of feels like a lost of power. Like I am dragging the back end of the car. Sometimes as the rpm's fluctuates the car will slightly surge. Furthermore, after the car sits overnight in the morning it is hard to start. And it starting to get harder. No grinding or clicking noises during starting. Furthermore, the engine while pressing the gas pedal sounds louder than it should be. Sometimes when I need to press the gas pedal hard and quick like when you merge onto a highway there's a little delay. No check engine or transmission light and no stored codes.