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.
Saturday, July 11th, 2015 AT 7:55 AM