hard to start when cold and stumbles upon acceleration

i have a 93 grand am 3.3, that's hard to start after sitting overnight and stumbles upon acceleration. when the car finally starts it smells like gas and rich exhaust. when it reaches normal operating temperture it doesn't stumble and restarts fine. it seems like when it set's overnight it loose fuel pressure. I just changed the plugs and wires,fuel filter, put new o-rings on the fuel injectors,cleaned the maf,and iac, and replaced the fuel pump in 2005. also when i checked the fuel pressure its aroung 25psi and i know it supposed to be somewhere between 41 to 47 with the key on. I checked the fuel pump its ok, it been tested. i think its the fuel pressure regulator, but how do you check.