Help...When I reach about 60 or so on the highway, the engine starts a pretty loud whining / grinding sound. It also might feel as if it's losing power or maybe revving. The sound continues even when I slow down to local streets and when I brake. If I turn the engine off and then restart it, it is fine again.
Any ideas what this could be?
PS- 94 Jeep Cherokee Laredo 150k miles

I don't think your whine is coming form your engine. It sounds like You Pinion Bearings in the fornt axle might be the cause. I had this same problem and thought it was with the exhaust or something because it would do it when I would give it gas if I let off the gas it would stop, then it started to do it when I let off the gas too. It was all cause by bad Pinion bearings.