1991 ford Crown Vic.. Engine light flashes 3 times and goes out.

SOURCE: Ford Crown Vic p0300 random cylinder misfire

take a look at the EGR valve it could be either vacum controlled or electronic either way what seems to be the problem is that the valve is stuck in the open position until the engine warms up you can gently tap the egr valve with a small hammer or a screw driver and you can see that it runs smooth, now if the egr valve is vacum controlled replace the valve. if it is electronoc controlled replace the valve and the module for the egr valve.

SOURCE: 2007 crown vic 4.6 l idles high on startup

This sounds like a normal condition.What happens is the cold start emission reduction component monitor(software program in the computer) is running.
Cold Start Emission Reduction Component Monitor
The Cold Start Emission Reduction Component Monitor was introduced for the 2006 MY on vehicles that meet the
LEV-II emission standards. The monitor works by validating the operation of the components of the system
required to achieve the cold start emission reduction strategy, namely retarded spark timing and elevated idle
airflow.
When the CSER strategy is enabled, the idle air control system will request a higher idle rpm, elevating engine
airflow. While this CSER elevated airflow is requested, the low airflow test compares the measured idle airflow from
the MAF sensor to the commanded idle airflow from the idle air control strategy.

SOURCE: Wiper motor replacement for a 99 crown vic

I replaced the same part on a 1994 Crown Vic. There are a few bolts which go through rubber mounts on the firewall and that is how the wiper motor fits against the firewall. There is a clip on the wiper drive that must be pressed and slid off the wiper shaft. The hardest part was getting clearence between the engine and wiper motor. If I remember there was a way to turn the wiper case to clear the engine. I have asked myself why this was engineered like this? There is nothing important in the way that 3/4" of clearance could have been given for removal.

SOURCE: 1998 ford crown vic sputters

I would try to replace your spark plugs, and spark plug wires, My 88 Vic did the same thing...now it runs like a champ....you could also try fuel injector cleaner.

SOURCE: Replace horn on 2006 crown vic

I believe once you have mounted the horn and connected the wire you will find that the horn wire was cut at (by) the steering coloum that the siren override was hooked to,you will have reconnect this,I hope this helps you