Several days ago, my 2003 Kia Sedona began running rough when the engine was cold. Van started fine but sputtered and hesitated - like it was running out of gas - until engine warmed up to running temp. It stalled once when driving at very low speed (foot not on gas). Because it's so hot and humid here right now (NC) I like to go out and start the car, get a/c running good, so kids aren't dying in the back when we go somewhere. The car began shutting off each time I returned into the house. It was a bit low on coolant and oil so we added that and it seems to have helped. However, it's now "chugging" and vibrating hard in the exhaust at about 4000 RPM. There is a tiny bit of soot mixed with water below the tailpipe on garage floor after revving it high in the garage. Any thoughts? Engine light is not on. 110,000 miles on it. Tune up was done at 104,000. For what it's worth, I drive low miles each weekday (5-10), more on weekends when husband is off work and we take the kids somewhere. I've put about 5,400 miles on it in 8 months. Thank you!