The Higgs mechanism for imparting masses to gauge bosons and matter particles is obviated by showing that Yang-Mills gauge bosons have intrinsic nonzero masses (rest-frame energies) from self-interactions. Electroweak (EW) mixing is ruled out because it produces a photon field that is massive, carries EW charge, and does not satisfy Maxwell's equations. Other fundamental difficulties of the Standard Model are identified. A new gauge theory of electromagnetic, weak and strong interactions is derived from the Dirac equation with no other postulates and no free parameters. The three forces are intrinsically unified, the photon field is Maxwellian, weak interactions derive from spin (not isospin), and the weak and strong bosons are naturally massive and chiral. Charge is naturally quantized to integral values. Three generations of lepton pairs and elementary-hadron pairs, all with integral charges, are predicted, contradicting the phenomenology of fractional quark charges, but in full accord with experimental data on weak and strong processes and composite hadrons. Neutrinos are massive. The Dirac masses, the fine structure constant, neutrino oscillations and Cabibbo mixing are shown to have a common origin in the gravitational field. The new theory leads to a new interpretation of "negative energies" with cosmological implications. Finally, it is shown that key expressions of the EW formalism agree with those of the new theory and with experiments only if the mixing angle theta is given by sin(2) theta = 0.25, which accounts for the EW model's successes.