start issue

Few months ago I installed a mspnp2, along with GT40P heads and intake on my 95gt, idling has always been an issue but the startup creeps to around 3k and hangs there for 4-5 seconds before dropping down, this is only when the car has ran in the last couple hours, cold starts in the morning...

2003 V6 Mustang. In dry weather, the car just starts fine. In humid weather, especially after it rains; it doesn't start, but still cranks. I checked the ignition on one of the spark plug wires with an ignition tester and the spark is there. I also tested the fuel pressure at the schraeder...