97 Monte Z34 brake system and PVC questions

[dsefzik]

I own a 97 Monte Carlo Z34 I bought it used in 2000 and have had a realativly problem free experience up untill a few months agoo all that had gone wrong with the car had been an alternator. From what I have been able to find onthe net this is not an uncommon occurance for GM automobiles. Recently though I have run into some problems that I would appreciate some help with. Recently I have noticed a clicking sound in the dash that only happens when the brakes are applied and at highway speed the LO TRAC light comes on. I am thinking this may have something to do with the ABS system? I was wondering if anyone has encountered this before and may know what it might be. I took the bottom panel off and looked around inside the dash for any cable or such that maybe responsible for the sound and found nothing. I was also wondering if anyone can tell me where the PCV valve is located because my car has just started to idle rough and heard that this maybe a cheap quick fix for that problem.