I just had it serviced for valve cover gasket due to oil leak that burn on starter area. then had it tune up but when I picked it up I noticed it shakes a little bit a time as I drive it. I thought it was just the road but I parked it and still running, it still shakes, like rattling. Please help me. this is a loan car from my son who is volunteering to make a difference for our country. i lost my job, now I need this car to find one soon. Help me please.