Q: rapid acceration of the engine when stopping

It's a 4cyclinder engine. W/T model, nothing fancy. When I come to a stop, about 50% of the time, when it wants to, I do nothing different, the RPM's on the engine jump up, with my foot on the brake to about 2-2200 rpm's and it's gone down to 1st gear and the car wants to pull forward and and I have both feet on the brake and you hear that creaking sound in those pads when the truck is trying to go forward. Then, out of self defense, I push it in neutral and it jumps to 4000 rpms and stop the truck. When the light changes or I pull off from the red light, take my foot of the brake, the rpms drop back down to 1000-1100rpms where it stays when this incident doesn't happen. Had it back to the dealer, which has a good shop, very nice, usually fixes anything, and the first time, about 6 months or so ago they said it was the hill assist and nothing they could do. I took it in about 10 days ago and they said it never did it on them. It did it on me before I left the lot? Got a clue?

My car has 15533 miles.