I have a 1990 starts and runs good in town. Once the engine warms up and I hit 60mph it dies(runs fine 50-55). If I pull over it will start right up and run for about a half mile then die again.
Rebuilt carb over winter, new plugs & coil, Lucas in gas.
Any ideas?????

 

Next time it dies undo the filler cap and listen closely. If you hear a brief rush of air it is due to your breather being blocked. Another possibility is a blockage of the gas-tap filter, which will require draining the tank so you can remove it to clean. A further possibility is a loose electrical connection in the ignition circuit (needs patience to check!), even a faulty ignition sender.

So several possibilities. Don't spend too much time on this. If you don't find it soon go to a local dealer or indy.