I have not seen a thread exactly like this, so forgive me if it's been talked about. I always keep gas mileage totals when I fill up and this last summer I was averaging 19/21 in the city, stop and go driving, and 25 on the interstate with cruise control. 4 months ago I had an ignition coil replaced and since then my gas mileage has plummeted. When I was driving around on the bad coil I was getting just slightly worse than normal gas mileage, perhaps 1-2 mpg less. After the repair I started noticing I was only getting 20 on the interstate, then I took some in town measurements and I was getting 180 to a tank (that's 10 MPG). I let my car warm up for 30 seconds, don't drive fast/accelerate hard, and I have a V6 with the 5 speed. The last tuneup was about a year ago. I also find it odd because this summer I had the AC on all the time, now the AC is not on. Any ideas would be appreciated before I take it to Ford so they can stick it to me with their service rates.