2000 Cadillac Deville 2000 Deville OBDII codes P0302, P0101

Have you had the fuel pressure checked, the fact that it won't start may, or may not make the codes relevant. How long has it been since it had ran, and was there a misfire or rough run felt(p0302 misfire #2). The two codes that relate to the mass airflow sensor are suspicious. Try and get it to light off on some starting fluid through the throttle body, if it starts and runs for a minute or so, you could have a fuel problem. You could also have a plugged catalytic converter not allowing air to be drawn in, if it can't exhale, it won't inhale. Check to see if you have injector pulses on at least 1 injector, and if you have good fuel potential. If all is good, I would say disconnect the exhaust pipe before the converter and see if it will start then. Fuel pressure should run 40-45 psi. It is capable of running with the MAF sensor disconnected, it just substitutes a value, so I don't see a need to replace it yet(unless it's too late).