300E Gas Mileage -- 10 MPG City!

Hello,

Before I spend more money on parts, I want to know more about what to look for in my hunt for much better mpg.

Car is a 1990 124. Fuel distribution systems was replaced about two years ago.

I have pulled the plugs (coppers) and replaced them about 1000 miles ago. Tan in color on the old plugs and they came off easy. So far, so good.

New air filter, oil (Castrol GTX 5w-30) changes with filter, new alternator, car starts first try on very cold winter days so I don't think the OVP is bad. No warning lights.

New vacuum hoses by idle control valve, air cleaner box to valve cover and from valve cover to manifold.

Car idles slightly rough at times and others it's smooth as silk. Car hesitates when starting off but only intermittently.

Gas mileage on highway about 20mpg in city about 10 to 12 mpg.

I've searched the archives but it seems that poor gas mileage is associated with hard starting. Not in my case as it starts usually on the first try.

I suspect a few items but I thought I'd ask first and see if I'm thinking in the right direction.

Any thoughts?

chicago124