2006 Pontiac Torrent Help!

Running rough is due to a misfire. How long since the spark plugs were replaced?

For noises you have to have a live person listen to it to determine which area of the car it's coming from, what affects it, what it sounds like, and things like that. Cars can make hundreds of different kinds of noises, so it's impossible to diagnose until we have those details.

The place to start is by having the diagnostic fault codes read and recorded. The people at most auto parts stores will do that for you for free.

At the mileage you listed, some of the more common suspects might be a vacuum hose that's cracked or leaking, or some other vacuum leak, a worn or collapsed engine mount that is allowing normal engine vibration to be transmitted into the passenger area, and perhaps a weak ignition coil. A worn mount can transmit vibration by allowing the two metal parts of the assembly to transmit engine vibration, and hat can sound like a grinding noise. That will usually change when turning the steering wheel one way versus the other way. Doing that puts forces on the engine that can push it a little to either side.

If there are no related fault codes, your mechanic will connect a scanner to view live data to see what the various sensors are reporting.

I told you already. Start by having the fault codes read and recorded. There are well over 2,000 potential codes, and only about half of them result in the Check Engine light turning on. That light never turns on for the other half of the codes.

As for the PCV valve, that is an inexpensive thing to try, but otherwise we never throw random parts at a problem in hopes one fixes it. That is the most expensive and least effective way to diagnose a problem. Your mechanic will perform tests to determine what appears to be the cause of the problem, THEN replace a part, then verify the problem is solved. There are dozens of things that can cause the symptoms you described, so just because someone posted the part that was their solution, doesn't mean it's going to solve your problem. If it was that easy, we would just compile a list of symptoms and the parts that solve them.

The next thing is to have your mechanic use a scanner to see what the Engine Computer is seeing and responding to.