Hmm let's see...we'll take our best-seller, and let it stagnate for a few years, then we'll redesign it to look like a frog, but be sure to not really improve the quality of the car a whole lot.
We should offer two engines of the same displacement, but...we'll make one of them a pushrod motor! That will really show people we are crazy!
The only problem is that we are not sure why the car doesn't sell...is it the poor resale value, the fact that they start rattling apart after 50K, the uninspiring styling, the lackluster features and engieering, or because our customer service sucks?
Take the Lincoln LS, put a cloth interior in it, get rid of the fake wood, maybe throw on AWD, which would help both the LS and this car. Get the ponies up to about 250, and sell it as the new Taurus.
Don't make the car look like a spaceship, and offer a wagon, maybe even not unline the Audi Allroad/Legacy Outback. Offer a high output version that will snuff the G35, 530, 320, and 3.0 VW/Audi...something that can build 280HP today, and can run reliable at 325+ HP (leave some running room since the auto industry is in a HP war with no sign of slowing down)
Make it reliable, and economical to own. Make it have features, make it run for 100K and not rattle. Give good customer service. Require your service advisors to be professional, cordial, and treat people right. Fix the problem the 1st time, and engineer it so it doesn't happen on next year's model. Strive to improve the product for the long term (if you are going to use the same damn chassis for 20+ years, a'la Fox body, then work to make it the best it can be!) Most of all - make people feel that they bought a Ford for more reasons than "it was cheap" and "I buy American only". The reason should be "I want the most for my money".
If Ford is going to use the LS as the new Mustang chassis base, why not use it for their bread and butter car?
And get a damn motor that can be used across the whole fleet. Nissan does it and they do it well. They took the same V6 that was in the 80's Z car, put it in the Max and their truck, and the rest is history...a decade plus later and it is regarded as a top 10 engine, even going in the new Z pushing 300HP.
Maybe take the 4.6L Ford, trim off 2 cyl, or use the 3L Duratec? How about the Rover 2.5?