69 Dart Hard to Start When Hot, Starts Fine Cold. Vapor Lock?
Oh, hey, you've got a '69. If it still has a 1969 carburetor and air cleaner, then it still has
this throttle plate anti-ice system, which is thoroughly unnecessary with today's gasoline formulations. All it does is heat up the carburetor like a teakettle and cause a rip-roaring case of percolation: fuel boils in the carb bowl, overboils through the nozzles into the intake tract, and floods the engine. Bypass it by removing the metal pipe from the carburetor throttle body, installing an appropriately-sized invert-flare/hose barb fitting in its place (I think it's 1/4" IV-flare, but could be 3/16"), and connect the rubber hose directly from the nipple on the underside of the air cleaner baseplate to the new nipple you just installed on the carburetor throttle body.
Until then, the get-by method is to floor the accelerator and hold it there (no pumping!) while cranking the hot engine.