1990 Sedan DeVille, 2003 DeVille
2003 Deville... I have had an issue where when sitting idle in drive the engine will jitter and return to normal. I will feel the same jitter when coasting and accelerating sometimes and that can be a bit heavier than when sitting idle. If the A/C is running it is more noticeable. When driving it runs fine but the acceleration will sometimes increase even if I am holding the accelerator steady. I have NO CODES. I get terrible gas mileage (around 10 to 11mpg average). I am thinking either I have a bad injector(s), bad spark or maybe a weak fuel pump? I am kind of stuck as to what I can look at next or consider to be an issue. Anyone have any thoughts?