66 mustang 289 stalling

Check the timing.

The issue is either ignition or fuel. These old cars are much simpler to narrow it down. I would guess it's a fuel issue. Might be a carb issue. Your brother took the carb apart? 2 bbl or 4 bbl? I wonder if something didn't go back together correctly or came lose. When you start it does it idle ok? Can you give it more gas and increase the RPM or does it stall when you give it gas? tennisshoe is right, you need to replace any old soft parts in the fuel system as this current fuel will eat up those parts. I need more info as to what it is going to trouble shoot it. Look inside the carb and see if it is squirting fuel when you give it gas. Could be a gas line issue depending on the shape of your gas tank. So if gas is coming into the carb then it is an ignition problem. You replaced the right parts but they have to be replaced correctly. Anyone of those put on incorrectly will cause running problems. So it runs for a short time then dies? While you are driving it or in the driveway?