I have taken my 93 camaro to different shops regarding a noise that happens when I drive up a hill. It doesn't matter if I'm going 40 or 80 miles an hour. When going up a hill it will make a noise like a hollow grind. It lasts for a short time. One mechanic said it was the fuel pump and changed it. But that wasn't it. I also just put in a new engine. It happened before the engine went out. Does any one know what it could be? The mechanics I have taken it to do not know.