What's wrong with my Car?!?

Several months ago, I drove my 2001 Mazda Tribute through a low water crossing where the water was pretty deep... every since then it's not been running right. When I'm taking off it kind of sputters and jerks, kind of like it's missing and it does it quite often going down the road. Sort of feels like a vac hose is off? Could the water have caused something major ? I just had the ERG valve and the spark plugs changed - as they were the only thing showing up on a computer read out.. it didn't change anything - and the mechanic has no idea?! Please help..