Random misfire

I have a random misfire and am stumped. I changed the cap and rotor, plugs, EGR valve, mass air flow sensor, ignition module, ignition coil wire and sprayed carburetor cleaner around intake to check for leak and still the same problem. When I first start my car it idles fine, but after a few minutes it starts to miss and idle really rough until I give it a little gas while in park and it is fine again for a few seconds then starts again. I notice no problems when actually driving the vehicle only seems to be at stoplights or just when I am parked. Please help!