is the balist resistor good? some times you can check them by how loose the terminals are(there is another test for this but ill have to look in my books). is the coil new? you could test it at operateing temp with a volt/ohm meter(bad coil could fail at operating temp) check with spare if you have one . does the car have a vacuum leak / spray flammible carb cleaner (carefully with air cleaner off) around intake manifold / check for loose and rotton hoses. is the timming still set right ?(set with gauge) set the idle mixture screws at highest vacuum then set the idle with car in drive with someone in car foot on brake (automatic) .
theres more this is good for basics.