I do 178 for three hours and I flip every hour, the sheath is on four layers of card stock. Make sure that the oven is up to temp before ya put something in. Coming up to temp, many ovens have a very wild temp swing. Folks that temper their own knives in the oven have been bit by this a bunch. The oven needs to be already up to temp before putting sheaths in there or bad things can happen.
Keeping it in the water till it stops bubbling sounds like too much water time to me. That is the recipe for casing leather. Sink in water till the bubbles stop, wrap your leather in a wool blanket and then work the leather the next day. The idea there is the water to uniformly penetrate the leather and then uniformly evaporate so that your leather is "plastic" the next day and ready to cut, stamp, shape and work.
Wet molding uses a wholly different moisture content for me. I put a sheath or holster in my water bucket till it starts to sink, not till the bubbles stop. I then take it out and put it on a towel. While in this state I trim any excess leather off the bottom side, I sand the edges smooth, punch slots if it's a pancake, edge the edges and the slots and power rub the edges. All this is done before wet molding. My sheaths might be out of the water for 30 minutes to an hour before I wet mold them as more often than not I'm doing the same processes to multiple items. What you are looking for is leather that is just about ready for its color to come back. If you wait too long and the color is changing back, its too dry, I will lightly add a little more moisture with a sponge. It will mold well if the color is changing back but you will make darker burnished marks where you are rubbing with your molding tool. Thats why I will add a little moisture to prevent these darker areas. So after rubbing the edges and all my sheaths and holsters on the towel, I go in and preheat the oven. I come back out and sit down and mold all the sheaths and holsters etc to their respective items. This might take 15-30 minutes to wet mold everything, sometimes depending on quantity, longer. We have a double oven stove and I sometimes use all the racks in both ovens. I get everything on cardstock and then into the oven and I start a timer.
It's too bad ya couldn't get on line to check yesterday. This time frame and water saturation is discussed in the pancake tutorial. If ya got twisting and pretzeling going on you are too wet or too hot or both, I would think. Wish ya could long trot on over for an afternoon in the shop. We could get ya lined out.
Speaking of that, Chris here has asked, (and I do appreciate him asking), if he could email me any specific questions and I want to extend that yes answer to anyone reading here. It might take a little bit to get back to you as I usually do my correspondence in the early morning and then again not till the next morning, but I will get back to you and I'll be glad to help if I can. My email is in my signature line here.