Linda. I replaced our Sharp with the SS GE profile microwave/convection unit about 5 years ago. After 3 years of traveling on our "shake, rattle, and row" roads in our great country, the top front hanging bolts actually almost pulled up through the top of the very thin metal of the oven. Fortunately for us, I noticed this on a annual test of everything that could come loose or fail.
I fixed it quite easily by taking strips of 1/2" by custom length metal and bending a "turn/straight length/turn" and mounting one on each side of the lower bottom of the oven as a hanger. I anchored the top to the bottom side of the oak overhead cabinet. Painted them black and they are almost not noticeable. The problem is now solved. Two years later and all is well.
With two Stanley brackets at a hardware store, a hacksaw, a metal file, drill, drill bit, and a bench vise you can do it easily and virtually no cost.
This was done in our 98 Patriot 37' Ticonderoga.
Larry Fritz