OK I'm stumped....I have checked everything I can possibly think of and still no solution.

The issue, whenever it rains hard or an all day rain, the Focus wants to sputter. It starts up fine and idles with no problem but when I depress the gas pedal it sputters and kicks like it's missing or something. After 2-3 miles it smoothes out and runs normal. It acts as if water or moisture is getting in somewhere and after it runs for a while it dries the water out, don't really know. It does the same thing if I go to the do-it-yourself car wash ( I'm not washing the engine bay, the hood is down).....but not if I wash it at home with the garden hose. It's really annoying.

It's an 03 ZX5, ATX just for the record.

do u have an aftermarket cai? plus have u taken it to get checked...sounds like u have water getting in. good luck let us know.

Might want to check to see if there is water in your spark plug chambers too.

I had this problem when i had my aerostar. I know it's completly different but when the van did that it ended up being something wrong with the ignition wires, somehow moisture in the air was getting in them.

I have the Volant intake. It may seem coincidental but it started when I installed my header, hi-flo cat and flex.............can't see what that would have to do with it though.

Could be the cat you put in

Could be water inside the distributor cap? Condensation?

The cat??? It only happens when it rains, how would that effect the cat?

i have the same problem. runs fine when its not raining..

Ever had anyone look at it......ideas as to the cause? It can be real annoying.

I have a new 2004 PZEV ZX3 and I kinda notice different behavior when the air is very moisture-laden. I know that the air intake for this newer engine is up in the front near the left headlight, and I also know (from the latest focus fanatics mag) that there is a restrictive mesh cover on the intake. So, maybe the spray from the street restricts flow until the engine area is warm and is evaporating the mist faster. I'd say my hesitations and sputters are VERY minor (esp. compared to a "bad fuel" fiasco I had in the first month of ownership), but I do see some of what you are describing in my new car too.