This might be a repost , but I was out today and just as I got up on plane it felt like the back of the boat had a quick slide out to the side , then it would be fine. This is a new motor it is a Merc 150efi on a 482 Nitro no jackplate and the motor is 2 1/4 inches above the transom. This was the first time since break in I have been out.
Have you waxed the hull underneath? A dealer once told me not to wax the chines or you could lose traction while turning.
How much of the pad are you supposed to leave alone, I haven't waxed it yet but maybe the dealer has(it was a bass pro shop ~rant)
Waxing the hull doesn't make it slicker in water.
It sounds like you experienced a little blow out of the prop. I presume this was at full throttle.
When a prop looses grip or bite it will cause the back of the boat to lunge to the side as the prop slipps then gets bite again. Somtimes this can be so violent it will cause the boat to spin out. Most cases blow out will only drop the boat off pad and trimming down will let the prop bite again and pick the hull up.
Water sticks to a slick surface the fastest surface on water is one that is areated. Meaning a sanded bottom will be faster than a waxed one. Fiberglass doesn't make a true 90 degree and has a rounded edge. Water tries to wrap around and suck to this rounded edge. Sanding the back edges of the running surface to a true 90 degree allows water to shoot straight off the back of the boat and run free. You'll see a lot of race boats that have been sanded the last five or six feet of the running surface and the trailing edges are squared off.
IT's not practical for most bass boat owners to do this the term for this is called blue printing the bottom.
I had the motor lifted up to the last hole and now it seems to be ok. I hope this fixed it.