My 1.8L Sport is idling rough and cutting out under load. It will still run at speed but I have to feather the throttle to keep it from "hiccuping" The check engine light is not on and I just changed the fuel filter. The local muffler shop checked my cat and said it is hotter than normal but still open. My guess is the coil packs are misfiring. Any other opinions before i drop $100+ on each new coil pack. By the way this all got worse after a Mudfest when the engine just pretty wet and muddy. It ran good on the way home but got bad after I powerwashed the motor. My mileage has also dropped to 13-15 mpg. Granted i'm running 31's with the stock gears but that is CRAZY low. Any help or opinions would be appreciated.

This may sound stupid and obvious, but try getting new plug wires.

Try misting a little water in the engine compartment at night while revving the motor. If you get a light show you'll know it's the wires.

I do not have "plug wires" like most . The DOHC has those coil packs on each cylinder. The wires going to each one are like 20 gage, very small. I'll try the night thing though. Thanks

My Chevy truck has the same system. Wires are about six inches long each.
Believe it or not I've had them short on me just like the conventional system.

I believe the voltage it much higher on these systems. That makes a short even more likely. 

Thanks man, I'll look for the short. 

Bit the bullet and bought 4 new coil packs. I found them on ebay from rockauto for $95 each. The cheapest ones around here were $135 each. Needless to say $400 later and the problem is fixed  I just hope my mpg goes up now also.