What would cause hard starting low rpm and stalling

Should the pressure at the shrader valve bleed off after the pump primes it to about 64 psi engine not running? Also when running the pressure jumps around at about 57 psi.. usually start right up when cold about 18f out. Once warmed up though if you kill and immediately restart it fires right up if you let it set for a few it has to be cranked for about 5 seconds before it will restart.