Ford Crown Victoria overheating

Did you get the air out of the system? Air pockets can cause issues.

15 seems low. Ford gives a spec of 40-70 psi with the engine speed @ 2500 rpm engine hot. Most cars I see are around the 25 psi @ idle. If your idle is lower than it should be it will make your pressure lower. This should be a direct reading on a good mechnical engine oil pressure gauge.

You can not clean them they are sealed in molded plastic. Buy a new one, tem min job to replace.

Dirty fuel system combined with a dead fan clutch?

HOW BROKE IN A 1998 CROWN VIC TRUNK

have a 97 crown vic,
in warm weather it idles fine and run fine
now that its cold I have to hold at high idle to have warm up
for about 10 mins.
if I just start it the engine will die with out me holding on foot on the gas

it's funny to be reading about a similar situation i'm having. i also have a '97 crown vic, bought at a municipal auction.
of course, running the a/c should put more load on the engine and produce more heat. but not enough to be concerned about. if you car seems to be overheating, the thermostat could be to blame.
while diagnosing a different matter, i noticed the coolant temperature at one point reached 217 F. i'm going to replace the thermostat as it may only be opening partialy. my temp gage is normally just above the half way point between the high and low marks. it hasn't gone any further towards the high temp mark to be alarming.
where is the needle pointing on your gage? have you replaced the thermostat?

a late opener will make it run cooler as it cools the radiator for longer

you mean 70-80 kph? because in mph that is very fast! check your thermostat, and if its not a problem with the thermostat sticking , it may be a problem with your water pump

when you hold the accelerator does the vehicle stay running? if so the problem is in ithe IAC idle air control motor, take a small screw driver and using the handle tap the iac motor and usualy the motor will kick in and the vehicle will run fine then if the problem is rectified replace the IAC