How do I clear the codes after changing fuel filter on 2000 mercury grand marquis

Question edited for clarity.
Question moved to model category.

That is a lot of items changed for nothing. The flashing anti-theft light was telling you the answer.

Key

1. Insert the key into the driver's side door lock.
2. Turn the key once, but not all the way to unlock the door. Leave the key in this position for 40-60 seconds. ...
3. Do this again, but turn the key in the opposite direction.
4. Remove the key from the door, get into your Ford, and start the engine. The system should be reset.

How to Reset the Anti-Theft System on Your Ford

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And also this!

https://www.crownvic.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=3731914

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If you don't have access to a scan tool just disconnect the battery for about a minute that will reset the ECM

If you need further help, I’m available over the phone at https://www.6ya.com/expert/david_4c166ba81493f541

See this :
How to change the lock code of mercury grand marquis without the factory...

How to change the lock code of mercury grand marquis without the factory...

I answered this already

If a MIL Lamp is flashing please do not use the car

That on a ford that is called a Class A Cylinder misfire & will
destroy your exhaust converter, as well as possible other
engine damage,work on the misfire issues

On your 2000 Mercury Grand Marquis 4.6L SFI , the Fuel Filter is located: Under vehicle, passenger side, below seating area, passenger side of fuel tank, mounted on frame in fuel line

it is attached to the frame near the rear passenger side door by a hose clamp, so you need a screwdriver to loosen the clamp, and pliers to remove the lines.

would certainly change those also

You have a described one of the coils going bad. You need to ru na power balance test to determine which cylinder it is so only one is replaced.

Time to go get it diagnosed. Could be a tunup issue or cranks sensor or fuel pump. You most likely have a code stored to help diagnosing

It wouldn't hurt to change the filter, but it sounds like you got a bad batch of gas, if it was running good before you got gas.
Get a bottle of dry gas and put it in the tank, if there is any water in the gas, that will clear it out, also it wouldn't hurt to put a bottle of fuel injector cleaner in the tank, I use that stuff all the time to keep the fuel system clean.

It may be a leaky injector. The injector is connected to the bank. 1 of 2 fuel rails.