420SEL 11 mpg!!!!

[E150GT]

Well, i have been dealing with 11 mpg lateley with my '86 420SEL. It started this when it started getting cold out and my car would not warm up past 60C. I did change the thermostat and oil, and it rund just a little above 80C in all conditions. I thought that ought to solve my bad fuel mileage issue but to no avail. I know a couple things need to be changed. One is my rear shocks. I know that can affect my mileage, but I don't think that would cause 17.5 mpg to go down to 11. Another is maybe my distributor rotor. I have not replaced it yet. Then I was thinking maybe my ignition coil because sometimes if I give it gas it hesitates. This is rare though. I know there are a million things out there that can cause this. I am wondering if anyone has some suggestions. The wires are 2 years old and plugs are say 6 months to a year old.