Help with oil leak...

After going through all of that, even head gaskets, I'm surprised you didn't change the valvue cover gaskets.
Yes, these leak as well.
If those aren't the problem, then I'd look into the lower intake gasket again, and make sure you have that sealed correctly.
The 5.0's also have a tendency to burn some oil as well as they get more mileage on them, so maybe not all 2 qt's worth of oil is leaking out.
HTH's

Valve cover gasket leaks are very common - you did't put new ones on when you changed the head gaskets? Stange....

The other to check/renew is the pcv system. If the pcv system is clogged, crankcase pressure will build and it will force oil out of the weakest seals in the engine - usually popping the dipstick out, oil out the valve cover gaskets, or oil out the front and rear main seals. It costs less than $20 to get new oil trap/screen, rubber grommet and pcv valve at the dealer. And that's where I'd get the parts -the aftermarket stuff is notorious for pcv valves that don't seal tightly in the grommet causing vacuum leaks. Even brand new valve cover gasktets and rear main seals will leak given enough crankcase pressure - be sure the pcv system is functioning properly.

Also make sure your not using cork valve cover gaskets. Ford makes steel stamped ones (that were put on 90+ mustangs?). They are expensive. Like $50+, but worth is as they don't leak and can be reused.

Also have you replaced anything lately? When did this oil leak start?

Clean your engine. Take it for a quick drive, and when you come back put newspaper or something under the car and watch under the hood.

Good luck.