I have a 2007 Chevy Tahoe that I purchased a few months ago. A few weeks ago I had just exited the interstate and was slowing down and the entire vehicle started shaking and there was some knocking under the hood. It quit after about 30 minutes. We changed the Brake Switch Sensor, and didn't have the problem again for two weeks. When it started again, the whole vehicle shakes, it is hesitant, loses power going uphill, and again shows the Service Stabilitrak, Service Traction Control and Check Engine light comes on. A week or so before the first episode the oil pressure went down to zero (I am unsure if this is related to it or not).
When you start up, it has a "lunge" like it would take off with you if it wasn't in park. Seems like it is consistently low with oil. While driving down the interstate, I've also heard a noise when going about 70mph and sounds like a scraping noise (lasts for a second) and then may do it once or twice more before getting off the interstate, haven't heard it but when you're going 70.

Computer reads that it has a Cylinder 4 misfire. We've replaced Throttle Position Sensor, EVAP, coil, injector, spark plugs and wires.

PLEASE help! Need some suggestions.