car fluctuates on 2006 Hyundai Sonata

Car misfires or fluctuates at speeds of 45-55 and when exiting the freeway (decelaration)around same speed. had a oil changed yesterday and today the check engine light came on the code was p2187 lean gas or fuel system faulty or ignition problems, car drives fine otherwise

Asked by for the 2006 Hyundai Sonata
The speed fluctuation is most likely from the lean or misfire problem. A code P2187 is a lean code, it does not mention misfire. Did you have this problem before the oil was changed? Maybe the oil change person accidentally left some thing loose? Did they check the air cleaner, that is where a lot of things can be left loose that will cause a lean code. I would take my car back and say that ever since the oil was changed, the CEL came on and ask them to re-inspect their work, free of charge.
Yes the oil change people will go back and verify their work. My fiance change the air filter over the weekend and maybe he left something undone will try and get Bradley at Performance Tires to inspect his work on the filter. The fluctuations has been going on since I perchased the car in November but the engine light never came on. I will take back to a Hyundia dealership on Monday and hopefully they can tell me why the car flutters at that speed. Have you ever worked on a car with a problem such as mine and if so what was the problem. How about if I rephase the problem as my car bucks alittle arround 45-55 mph.