Q: Rough idling and shaking on a 2000 Blazer

You’re a lucky man, you’ve had that thing for seven years and this is the first problem you have. I’m assuming you don’t drive that many miles. On those, a lot of times it is a vacuum leak. I’ve got a video "finding engine vacuum leaks with a cigar." It shows you how to look for the vacuum leaks. When you get a vacuum leak, it sucks air and makes a car shake. When you rev it up, since it is revved up and going fast, that little vacuum leak doesn’t affect the air-fuel ratio as much. So check for vacuum leaks. You might change the PCV valve, too. A lot of times, they just leak and they cost like ten bucks so you can easily change that. If you’re still uncertain what to do, you can enlist the help of a mechanic, such as one from YourMechanic, to inspect and repair your car’s shaking issue for you.