I'm going to show my ignorance on the mechanical side here 74 Monaco w/400 I'm looking into the seller stated could use a tune up. When I asked about that he said she's really sluggish to drive and he'd would not go anywhere long distance. What could be at issue here? Being 700 miles away I can't get a good read on that. I know my 81 Imperial w/318 can be a bear at times too. But I know why with that car.