Idle Rough, Stalling
 

I posted some questions a couple of weeks ago and want to thank those that responded. I am still having problems with hesitation, stalling, rough running, and sometimes up and down rpm at idle when the engine is cold. Below is my original post listing the things I have done to date:

http://forums.pelicanparts.com/porsche-911-technical-forum/539251-hesitation-acceleration-idle-stalling.html

Latest I changed the O2 sensor. At this point, all sensors have been replaced. Everything I have done so far has helped some, but I am still getting these issues. I did find some vacuum leaks with loose hoses that I tightened and replaced (some of the smaller ones).

I do have a new issue that I did not notice as much before. Under hard acceleration sometimes the engine stalls for a brief second and then comes back strong.

My question is that when I take off the vacuum hoses on the fuel pressure regulator or dampener, nothing happens. It does not matter if I take off the hose and plug it or leave it open, I do not notice any change in the engine. There seems to be good vacuum on the hoses and they were tight on the units so I do not think they are leaking. I also notice that nothing happens when I take off the oil tank cap. I have not been able to check the fuel pressure yet lacking a gauge. Does this sound like I still have some hidden vacuum leak or more likely a bad fuel regulator. I know I really need to get a hold of a fuel pressure gauge to check the regulator. Thanks for any help.

I still say you have a vacuum leak. I had a problem similar to this and air was coming in from the intake runner gaskets.
start you car up and pull the injector harness from each cylinder, one at a time and see if you can isolate the cylinder with the problem.

You should probably cut this post and paste in the old thread, and bump your old thread.

Off the top of my head it sounds like you need to check the air fuel ratio in the exhaust, just before the cat. And then work forward from there.

Thanks Rusnak,

I reposted under my old post so this one is now dead.