Why is my car loosing power when I'm driving along and it drops to a crawl.

“Lincoln dealers” .. ?

meaning all dealers who can work on Lincolns (Ford etc) My local repair shop cannot remove spark plugs from my Navigator

You must not have noticed but this question was concerning a Honda Fit. As for your Navigator .. Some shops simply refuse to even attempt to replace the spark plugs due to inherent spark plug breakage problems - ‘IF’ that happens - as sometimes it does despite the mechanics best efforts - then it’s pretty labor intensive to remove the rest of the broken spark plug - therefore ‘many customers’ do not understand why that cost so much.. On occasions - it’s just not worth the hassle - plus there are more profitable / less aggravating repairs waiting in the parking lot... I actually think the manufacturer(s) > (automobile & spark plugs) should share at least part of of the blame for your concern.