Depressing the gas pedal sets the choke and also causes a
shot of gas from the accelerator pump.
Most but not all MoPars start best with one full depression
and release of the gas pedal. Some carburetors, such as the
older Carters [Ball & Ball was the former brand name] only
require 1/3 depression of the gas pedal and holding it
there.
Read your owner's manual and follow that advice.
--Roger van Hoy, '55 DeSoto, '58 DeSoto, '42 DeSoto, '66
Plymouth, '81 Imperial, Washougal, WA