I took a few quick cell phone vids, not sure if the sound quality is good enough for anyone to diagnose from, but any idea's would be appreciated. https://www.facebook.com/video.php?v=10100462834348769 https://www.facebook.com/video.php?v=10100462834708049 https://www.facebook.com/video.php?v=10100462835606249 Yesterday was the third time my car has acted up after being outside during moderate to heavy rain. By acting up, I mean the sensation of misfiring, shaking at idle and hesitating under power. I've had several run ins with IAC related issues and this feels nothing like any of those. I asked around and received various advice such as water entering fuse box, something with plug wires, or the BCM in the fender well? I know everyone always says this, but I genuinely did try a search before posting this and could not turn anything up. The first time this happened I added some fuel system cleaner to a tank of gas and the problem went away but I think now that it has happened two more times and all three were during/after rain, that I doubt the fuel cleaner had anything to do with the fix and it was likely just that whatever got wet dried out. The car ran just fine into work today, as if nothing happened at all yesterday. General info about the car: It's a 1999 Mustang GT, ~68k on the odo. Mods include JLT Ram Air intake, Trick Flow Intake manifold, and Borla Catback exhaust. I do have the Steeda Q-400 cowl hood that is a rear heat extraction so there is a small opening on the rear drivers side of the cowl that water could theoretically enter the engine bay from? After I made it home I opened up the hood and searched around but could not find any standing water, nor did the air filter feel wet to the touch.