I have a 1999 Plymouth Breeze 4-cyl. 2.0L. My problem is that my car is supposed to get around 26 city and 28 highway MPG and for the first 9 months i had it i got that. But recently my gas mileage has been lowering majorly. my last take averaged at 17.3 mpg and i have been driving it carefully(kept under 2000 rpm-ish). I have brand new oil in it which is Castrol Edge with Titanium technology, so its pretty much top of the line synthetic oil. The car has 91,XXX miles on it and has been driven by my grandma its whole life till it was given to me, which i also drove it with care. If anyone has any other ideas on how i could fix my gas mileage problem tell me because gas is expensive nowadays and i cant afford it at the moment.