I had the same problem: at 50-55Mph, when accelerating, the engine would start shaking. When I released the acceleration the vibration went away. Also, it would shake badly when driving up hill and accelerating. Went to a mechanic and changed both catalytic converters (the first one melted and clogged the second one) did a complete tune-up, wheel balance and alignment. He also changed the rear engine mount. However, the van was still shaking but it was 50% better already. Next, he changed ALL engine mounts (supports) AND the right axle (drive shaft). Now the van runs like a champ and I could not be happier! I hope this helps. If you can do your own replacements you can save a lot of money!
The 2005 Kia Sedona's engine produces 218 ft-lbs. @ 3500 rpm.
The 2005 Kia Sedona has 24 valves.
The 2005 Kia Sedona has a V6 engine.
The 2005 Kia Sedona is a gas-powered vehicle.
The 2005 Kia Sedona has a 5-speed automatic.
The curb weight of the 2005 Kia Sedona is 4802 lbs..
The maximum payload of the 2005 Kia Sedona is 1157 lbs..
The 2005 Kia Sedona has double overhead cam (DOHC).
The 2005 Kia Sedona's turning circle is 41.1 ft..
The height of the 2005 Kia Sedona is 5 ft. 9.3 in. (69.3 in.).
The 2005 Kia Sedona is 16 ft. 2.1 in. (194.1 in.) long.
The 2005 Kia Sedona runs on regular unleaded.