This information can be found in your owner's manual, or under the hood on a placard. If you do not have one, then you need to get one. Dealer, E-Bay, Salvage Yard, and many online sites are sources for a manual. Use Google and search with the term, "Automobile Owner's Manual".
.054
Spark plug order? there is no such thing.
According to one of Fords websites : For a 1969 Mercury Cougar ( all factory available engine sizes ) ( .035 inch spark plug gap )
You can find the correct firing order for your 1987 mercury cougar at www.coolcats.com, it is a website dedicated to the cougar and thunderbird.
0.054 for 1999 to 2001 V6.
According to one of Fords websites : For the 1992 Mercury Cougar , 3.8 liter V6 engine : ( the spark plugs are gapped at .054 inch )
According to one of the Ford websites : For a 1988 Mercury Cougar , 3.8 liter V6 engine : ( the spark plugs are gapped at .054 inch )
1995 Mercury Truck Villager Van 3.0L EFI SOHC 6cylThe Spark Plug Gap.032 (In thousandths of an inch)
The Spark plug location on the 2001 2.5 liter dohc is under the valve cover.
According to one of Fords websites : For the 3.8 liter V6 engine in a 1988 Mercury Cougar : ( the spark plugs are gapped at .054 inch )
.040 ========================================================== According to one of Fords websites : For a 1993 Mercury Cougar : The 3.8 liter V6 engine and the 5.0 , V8 have spark plugs gapped at : ( .054 inch )
The plug gap for a 1995 model, 40 hp Mercury is .035 in.