MG Car Repair: 1977 mgb usa model imported to canada, ballast resistor, wiring loom

Question
my 77 mgb starts up really nice and runs fine until it warms up and she starts to miss and at a stop she wont idle anymore stalls out.after stalling out she will not start until it cools down to a certain temperature.new carb kit installed single weber sidemount new coil installed.coil on wiring diagram shows no ballast resistor for 77 required but coil heats up a little bit.any ideas thanks marty

Answer
My first reaction is that you have fitted the wrong coil.  My wiring diagram for a USA spec 78 MGB shows a ballast resistor inside the wiring loom.  If you have fitted a non-ballasted 12-volt coil, then you need to run an extra wire directly from the white wires on the fusebox to the white-with-green (+) terminal on the coil.  No need to remove any other wires, just add this one and see if the problem goes away.  

The other possibility is heat soak.  Fitting a sidedraught Weber immediately above the exhaust manifold is not a good idea.  The original carbs had a heat shield.  You may need to fabricate a shield to deflect heat from the bottom of the Weber.