Po171 /02 03

2001 Sonata 2.4 engine Here is what the car is doing. When the car sits usually overnight when i drive for the first few minutes the car lunges as if i?m driving fast. the car then drives normally this only happens if the car been sitting for a long time (overnight ) I got the code po171 01
02 . I change the air filter and clean the MAF sensor light went out and drove better for a few days. then the code came back po171 03 The lunging problem seem to be the throttle as i have not check that yet been searching this problem for about 4 weeks. sometimes the lunging goes away for a few days and then returns. I also clean the throttle body with throttle body cleaner. Any way i can check to see if the throttle sensor is the culprit .Any help appreciated When i drive around 100 kmh i can feel a slight hesitation but once i go over that speed the car runs great. I?ve also been checking for vacuum leaks so far no luck if i can?t find the problem soon i will have the dealer check it out. I just don?t want to throw parts at the problem