where is my vacuum leak, Checked all and can't find leak Options

[jsf322]

I am starting to go out of my mind trying to find my vacuum leak. I am having a very inconsistent idle. When the car first starts it idles fine for a minutes and then begins to hunt. I have posted on this before and had some good suggestions, but have found no answer. I have replaced all vacuum lines, fuel injector seals, intake manifold seals, throttle body seal, intake runner boots, checked the intake plenum for cracks, checked the dwell and timing, and the valves have been adjusted. The only possible leaks I can find is a hissing from the air screw on the throttle body and I noticed the cold start valve gasket was not the best when I removed the valve to check the intake plenum for cracks. Could one of these be the cause? Any other ideas. This is getting very annoying.