I have a 200 Kia Sephia and it only has a little over 55,000 miles on it. Recenlty the car atrted chugging and the ck engine light came on. I had it scanned and it said cylinder 3 misfire. Ok well I bought new spark plugs and had those put it. Ran fine for a day and then started chugging again and the ck engine light came back again. This time is was a random multiple misfires going on. Took it back again to the place I had the spark plugs installed and they found the fuel pressure regulator was leaking. So I had to get a new one of those. Got that had that installed and ran fine for a day again. Brought it back again and they didn't have a clue. They thought one of the spark plug wires was bad but they weren't positive since it checked out ok. So the next day I brought it back to the dealership since I called and chewed them out about the car and they checked it out for me for nothing. They said I was given the wrong spark plugs and that was my problem. So they put in the factory kind for the car and did a whole tune up. Again said it was running fine and the chugging stopped. Drove it home and the chugging started again. So I called and told them and brought it back the 2nd time. This time they found 2 engine coils were damagaged and a spark plug wire was bad. Again they said runs great no chugging. Once again I drove it home and the chugging began again. He was just dumbfounded when I told him that. so I had to bring it back the 3rd time. This time they think it has something to do with the gas like I got bad gas. Well they claim they drained the tank but couldn't get all the fuel out so they just put it all back in. Told me it didn't chug for them and to run the tank to almost empty and then fill it up with premium gas and a bottle of heet. Well like every other time I drove it home and it started chugging again but this time the ck engine light came back on again. I calle once again and they are just so frustrated with my car at Kia they don't know what else it could be. Does anybody have any clue what could be causing the chugging? Any help would be greatly appreciated. They say everything in the engine checks out fine and I don't want to take it to another place since Kia is not charging me each time I bring it in. HELP Please!!!!