Check Engine Light illumination—combined with a lack of power or a stumble on acceleration—may be caused by the throttle position switch (TPS). Kia released an improved part which should correct this concern.Google+
Car Problem Reports
Kia Sportage Faulty Throttle Position Switch
Kia Sportage Problem
Exhaust & Emissions Affected: 2.7L V6
Average Mileage: 83,518 mi (27,000 mi - 181,700 mi)
car lacks power may go up to about 20 miles then totally loses power
Visitor, 2007 Kia Sportage, 181,700 mi
Hard downshift when brake is applied. Changed TPS and had dealer clear the codes and it runs fine again with no issues.
Visitor, 1998 Kia Sportage, 156,061 mi
My 98 kia sportage hesitates while sitting or about to take off. When I give it acceleration it will proceed but at times stumbles when proceeding to go please help!
Visitor, 2009 Kia Sportage, 30,000 mi
Hit 30K miles exactly today. Noticed that the gas pedal was "sticking" slightly. Would step on the gas from a stopped position and have to press harder to accelerate and then the car jerks forward.