I am NEW to this site and hope that I am posting this correctly. I have a 2002 Toyota Sequoia and I thought my transmission was going out. It all of a sudden started with this problem. I feel like something is about to drop out from under the hood. It does it when shifting into 2nd or 3rd gear and it doesn't always do it. No lights are on. I had a friend mechanic drive it and he suggested that I take it to a transmission shop. I took it to the transmission shop today and the technician told me it was NOT the transmission. He described the problem as a HARSH GALLOP. He suggested that I take it to a Toyota Dealership and have them complete a computer update. Has anyone ever had or heard of this kind of problem ?