When I lived in the Upper Midwest, I turned around a lawn in a summer. First thing I did was to stop using weed & feed.

I applied a liquid weed killer as it's much better than the weed killer in weed & feed. My Dad still lives in the Upper Midwest, has a beautiful lawn, and has been having great success with this combination weed killer and preventative.

For the fertilizer, I applied a granular (not the powdery Scott's shit) from a local Mom & pop nursery (similar to HRK's recommendation). They had a multi-step program tailored for the area.

I had a rain gauge and made sure that between rainfall and using sprinkers that the lawn got the appropriate amount of water per week.

I also mowed the lawn the appropriate height with a sharp blade. Many people mow their lawn too damn short and midsummer their grass dies and only weeds survive. About halfway through the summer, I swapped my blade out for my spare blade so that I was mowing with a sharp blade.

Between the right chemicals applied at the right time, the right amount of water, and mowing properly the lawn made a huge turn around in 1 year.