The Stovebolt Site Forums The Shop Area Engine Shop runs rougher after warm up 1959 235

i was running without thermo just to eliminate making
sure wasnt going to heat up for check out.it runs really
good idles ect until gets a little warm then wont idle.
if i leave it alone start later same thing runs good at start up for about 5 mimutes drive a lttle runs bad.
i am running gas straight out of bottle container.
new coil and condensor.thanks