First thing in the morning, the car cranked over and almost started but then stalled. l have been unable to get it to even come close to starting. l did very recently fill it to about 3/4 tank with 87 octane gas (usually l get 89 octane and been doing so for years). This was 2 days prior and maybe 15 miles of driving since. Could it be ''bad gas'' or even have something to do with the change to 87 octane?

If it will turn over but not catch here is a short checklist:
1. Timing
2. Ignition Module
3. Wiring
4. Computer
These are most of the things that will cause the problems you have. There are a few others but these are the most common. Also, these are not in any particular order.

hi,

l do not know vehicle history & miles on car

it can be a number of things

check ur battery cables & make sure there is no corrosion
on battery terminals.it is fall season..if so, clean it..you
can go to autoparts store & someone can recommend a cleaning product for ur cables & also have them check ur alternator & battery for FREE.

May need to change ur starter & change ur fuel filter/pump

lowest grade of gas has nothing to do with ur car stalling.

if it is under warranty, have service shop check & make sure there is no electrical problems & have them check ur ignition.

hope all is well with ur car,

S

Water in the gas tank, Loose battery wire connections at the starter, corrosion on the battery terminals. Start with the stupid stuff first before you start eliminating the possible.

Check ur owners manual or call dealership up bec yes some engines or vehicles r octane sensitive & lower grade gas may cause problems.One easy thing u could do is try adding some high octane gas treatment to the gas & try rocking the car a bit to mix the octane additive & allow it to sit awhile a few hrs.
Try then boosting the cars battery but before u turn ur vehicle engines over do not pump the gas paddle just push it slowly to the floor & keep it there a bit as u turn the key.

Hope that helps & best of luck.By the way even a loose or rusty or corroded battery or stater or alternator or engine block post connection can cause such problems too.Also keep in mind that really gas filters should be changed yrly so if its not been changed in awhile change it & check the air filter too.

l drove a 2002 cougar for quite a while, and always bought plain unleaded.
so it is probably not a lower octane of gas.