Ford Motor Co. will continue building Mercury Cougars at its Lorain, OH, plant, instead of moving it to the AutoAlliance International Inc. facility in Flat Rock, MI, sources say. The next-generation Cougar and Ford Thunderbird may switch to front-wheel drive for the '98 model year, they say, in keeping with Ford's tentative plan for all passenger cars to be front-drive by 2000. The company will spend about $100 million for a new paint shop and body shop in Lorain. A Ford spokeswoman neither confirms nor denies the plans.