Misfire/Shutter After Engine Cleaning. HELP!
 

I had my engine cleaned/detailed today and am noticing a problem afterwards. I have an 03 GT (4.6L V8). When I accelerate, the engine shutters or skips. It occurs randomly, often in the beginning of each gear. It only happens when I am on the throttle and not coasting. It really feels like a cylinder is not firing. The engine acts completely fine in idle, even when reving it. I have checked all obvious electrical connections and hoses, and everything seems to be normal. I don't think it is a faulty spark plug as the problem suddenly arose after I had the engine cleaned. Any help or advice is appreciated.

Forgot to mention that there are no warning lights on.

water in one of the COP boots can cause this. I would start there.

I had the same problem with my 04. I had a leaky intake manifold and every now and then I would have to pull the cop's and stick a paper towel down beside the plugs to dry the water up. I also used some dielectric grease around the cop boot to keep the problem from reoccuring until I got a new intake. You shouldnt need to do that since you know what caused it but it still wouldn't be a bad idea for the future.

Spray WD-40 on everything, except belts of course, and wipe it all down. Sounds like water in something electrical. Possibly the coil pods.

My detail shop makes me sign a waiver before they'll wet down my motor. I don't do THAT anymore. Don't wash it again! Spent how many hours it takes to hand clean each and every nook and cranny in that engine bay. My car is an '03, and the motor is spottless. The whole trick is to spend 10-15 minutes each time you take her out, to clean various parts. That's what I've been doing for the 9 years I've had her. She has NEVER been in the rain, and I Sh*t you not; I keep her so spotless this way that in all the years I have owned her, she has actually been " handwashed " maybe 18 times in 9 years; and 9 of those washes were from when my Detail man comes to my house once per year.

pull all the coils and check for water/moisture. used to happen to me everytime i tried washing my engine so i stopped doing it

I have had that problem a few times over the years. I open the hood and put a big fan pointed down on it. Gotta dry it all out. It helps to pull all the connectors apart and put a piece of tape on them to aid in putting them all back afterwards. (so you don't miss any)

Moral of the story, don't use water to clean your engine bay. I've used PB2 also to shine it up after I used various things to clean the engine. Also believe or not, tire shine makes the engine have a nice shine also (accomplished this without even cleaning any engine parts).