2000 mecury cougar just replaced alternator plenty of battery power cranks but wont start

you'll have to see if its missing fuel,air,or spark.Fuel could be bad fuel pump,air something clogging air filter duct,spark bad coil,or coils,crank sensor.

You need a mobile lock smith or tow it to the dealer , nothing you can do ! Need lock smith tool or factory scan tool . No if ands or buts about it .

take a test light and check your fuses , make sure both sides of the fuse is hot ! check power at alternator if no power gos in no power will come out.

Does ur engine crank over? if so no spark or no fuel.

Hello u69men33, I am very sorry you're having problems, but, I do have a couple of thoughts.
My first thought is that you have a bad alternator. I say this because, once the engine is running the alternator output should be enough to keep the car running, even if the battery is weak.
My second thought is, and this seems less likely, your new battery doesn't have enough cranking amps for the make and model of your vehicle.
Many people are not aware that vehicles have a minimum cranking amp requirement for the battery that is determined by the equipment in the car. So, they just go and get a new battery that looks like it's about the same size.
A word to the wise, if you're not sure you got the right battery, call any parts store give them the year, make, and model of your car and have them look up what the minimum cranking amps should be, then, look on your battery to make sure it has atleast that many cranking amps. If the battery is new and has the right cranking amps, my money would be on a bad alternator.
I hope this info helps you.

check your starter

if the car cranks over and is getting fuel, then it's not getting spark.

could be a bad ground cable .replace battery cables if they havent been change in a while.if it still dont crank .remove starter have it tested.at advance auto parts and auto zone. if starter good.replace starter solenoid or relay.

Not sure if you got your cougar running or not, but I had a similar problem and it turned out to be my Crank shaft sensor. I replaced it myself, its fairly easy if you are the type that likes to pull stuff apart and fix it. The part cost about $20. you do have to move the ac compressor over but you don't have to remove it makes the job a lot easier. I am still running the 1997 cougar xr7 30th anniversary edition, it has 160000 miles on it and still running strong. I think these are the best cars mercury ever built, i hope they come out with them again in this body style and platform.

if no spark check into crank sensor, does rpm needle bounce wen crankin? if not its definately crank sensor