Hey guys,
So on my 1985 280 TE Station Wagon it has gone through a lot of work and I finally got it running very good. BUT the only thing now is after 30 minutes of driving the RPM will DROP to the point where I get scared it might die.
I have adjusted the fuel/air mixture valve to a perfect point so it runs great for 30 minutes or so but after lots of driving the RPM just BOOM shoots down when coming to a stop and or not using lots of gas.

Any idears?

It would be good to know the mileage of your car and what exactly the recent work was.