This is the third thread you've started on this topic. I think you'll get more feedback if you keep all your troubleshooting confined to the original thread so people know what's been tried and what's been offered in terms of assistance.
When I turn my computer on, I receive full signal. After 10 minutes, it get weak.. after 20 minutes the signal is gone. Then I turn off the computer for 40 minutes and It start to work for 15 to 20 minutes, then it goes off.
I did reset the PMU.
So I figure out that when the computer is hot the airport work bad...