I recently purchased a 1951 Lincoln Cosmopolitan with the 337. It runs but was missing on cylinder #3. Checked pressure and each was at 110 lbs, except #3 which had 90 lbs. replaced the spark plugs and it ran great on all 8. The only problem was that it began leaking a bit of oil from what looked like the middle of the exhaust manifold where the exhaust from #3 comes out. The cylinder head is dry. Any ideas? The car sat for 40 years and only has 64k miles.