Car Dies When it's Very Hot and Humid Outside

[pboxfun]

I've recently noticed a problem with my car and I'm trying to see if it's tune related or electrical. Maybe you can help point me in the right direction. The problem I'm having is my car stalls in gear at idle, like at stop light or waiting to make a turn. It will start up again but it sometimes takes awhile of trying. Weird part about this problem is that it only happens when it's very humid out especially after a rain storm. Other than when it's humid outside the car runs just fine and has no problems. It never dies on me while I'm driving either or misses. I did notice before the car shuts off the rpms act very erratic almost a 500 rpm variation. But when it's not humid out the rpm acts like it should. The only way I can keep it from dieing at stop is by pressing the throttle raising the rpms up while holding the brake with my other foot.

A couple months ago I installed a new opti, plugs, wires (otvc), alternator, and battery. The icm and coil has less than 5k miles on it since I've replaced them. I checked the fuel pressure to make sure it wasn't the pump and it was fine. Also there isn't any codes being thrown at all when this happens.

Does anyone have any idea what could be going on? Any help would be greatly appreciated!