I had these codes for a while. It used to jerk when moving from stop. My mechanic said it's the fuel pump and the jerk went away. He then found a ripped intake hose and I replaced it (see image). Code still not gone and now when I'm fully stopped whether in park neutral or drive there's the sound you hear in the video (I couldn't upload the video but it sounds like popping or marbles shaking coming from the engine sounds like engine knock but goes away when pressing the gas even a bit). My average MPG also went down a decent bit. From 19.5 - 15.7. Also, every now and then if I push it a little bit then stop at a traffic light then try to push it again it takes a long time to raise the RPM. Would really appreciate any help before I take it back to my mechanic. I just want to fix this and sell the car.

 

I dont know if this will help but do you hear the noise while sitting in the D seat? Mine turned out to be the fuel dampener. I never knew it even had it. The sound traveled along the fuel line. Three shops had no idea what it was. One guy said the power steering pump and another said the fuel pump. P0174 is what came with mine but I cleared it and it didnt come back? Three shops and weeks on the net and couldn't find it. Turns out it was real simple. Fuel damper on the fuel rail. problem fixed and codes never came back. Yes I could hear and feel the hesitation. Heck one shop told me that my timing gears were old and that was the problem.
Good luck.

 

I have P171 and P174 cannot locate any vacuum leaks yet can you explain how you identified and fixed your problem?

 

As a last act of desperation I called a mechanic who just graduated and haven't learned the bad practice of the R&R first time and actually crawled around. even then it was a shot in the dark but I had nothing else.