99 malibu problems, sound familiar

Recently my 2.4 140,000 miles malibu didn't want to start right up, it took about 5 or 6 cranks before it fired up. I changed the fuel filter and i thought my problem was solved, and it started up fine. 2 days later i was at my daughters school waiting to pick her up and the car sounded like it was going to stall out,rough idle,bucking, but it didn't. Now it only does this when its idling and pulling out at stop signs, its fine once you get going.It has been really bitter cold here for a while, -5 windchill and i dont know if that has anything to do with it or not.I' not getting any codes but i replaced both coils the iac valve,put dry gas,fuel injection cleaner and cleaned the throttle plate and port and had my injectors checked and there fine and the problem still persists.Im not sure where the egr valve andpcv valve are located? I've read dozens of posts here but nothing stating what their problem was.If anybody could tell me where the egr & pcv valve are located,or if you had a similiar problem and had a fix,that would be helpful! THANX!

I called the dealership and they told me there is no pcv valve or egrvalve on the 2.4 engine ,only the 3.1 has them, the pcv has been replaced by a water seperater,who knew!