Another suggestion

Sounds like your problem occurred right after your DIY. One possibility is that you accidentally did something else without knowing it. If one of your engine cylinders is not working (say due to bad spark plug or the wire connecting to the spark plug), then you'll experience loss of power. In this case, I suggest you check the wire connection that goes to the spark plug. Many years ago I had a bad wire connection to spark plug and everything appears to be fine until going uphill.