Car stalls when ever you come to a stop or slow down a diagnostic revealed several possible causes 1. knock sensor 2. 02sensor and 3. idle control

You will need to get a Good Mechanic to look at this. There are 3 completely different problems here so it will need to be properly checked out. I've listed the Trouble Code definitions below.
-The knock sensor looks for signs of the fuel igniting at the wrong point in the sequence.
-The Crankshaft position sensor checks the pistons are in the correct position for the engine electronics to be in the correct sequence.
-The Air Control system is a set of valves that adjust air flow through the engine when running at different speeds. (Slow needs less air, fast needs more air).
Knock Sensors and Crankshaft Position Sensors can be in some ridiculous places on an engine and usually need major surgery to get to them. Air control systems could be anything from a 'sticky' valve to a faulty sensor.

P0325 = Knock sensor (KS) 1, bank 1 - circuit malfunction
P0335 = Crankshaft position (CKP) sensor - circuit malfunction
P0505 = Idle Air Control System

Have you had it to a shop that has a professional type scan tool that can view engine sensor data parameters ? Do you know what those are ? Idle air control counts , mass air flow sensor data , MAP sensor , TPS - throttle position sensor , crankshaft position sensors , Cam sensors , engine coolant temp , intake air temp etc......

3 areas of concern are as follows:

1. Bad MAF (Mass Air Flow) Sensor - can cause erratic idling and stalling
2. Bad EGR (Exhaust Gas Recirculator) valve - erratic idling, skipping
3. Bad TPS (Throttle Position Sensor) controls idle under different conditions ie cold, hot, ac etc

Your problem may be any 1 of the 3 or a combination. Best advice is to get a free diagnostic test done (most chain auto parts stores will do this test free) and come back with the error codes, These codes will help to narrow down where the exact problem lies.

Several conditions could be the cause of your problem.

1. Bad MAF (Mass Air Flow) sensor - often responsible for erratic idling
2. Bad TPS (Throttle Position Sensor) - controls idle speed under all conditions ie warm, cold, + with A/C running.

It's possible to diagnose further by getting a diagnostic test done. Most chain auto parts stores will run a free diagnostic test to obtain a OBDII code (these codes specify which components are either failing or not responding) It is possible that a combination of both the MAF and TPS are contributing to your problem. If the car will idle when cold and only wants to stall once warm and under way, it's more likely than not to be the TPS.

Possibly a transmission issue. The transmission has a "lockup" mode, where a clutch connects the engine directly to the transmission at cruising speeds. It is then supposed to unlock at lower speeds and for stopping. If it doesn't unlock, the car will stall at a stop. Try putting it into neutral (carefullly, so you don't go into reverse) as you slow down, if it doesn't stall out, it is most likely the transmission lockup mechanism.

If it stalls in neutral it is an engine issue. Bad idle control, bad ignition (it's easier to fire at high speed), bad fuel injector, bad air flow/pressure sensor... and more possibilities.

First impression is a MAP sensor. If you take the car to a service station or an auto parts store that features free diagnostic tests, I'm sure the MAP sensor fault will appear. Other cause could be the TPS which controls the idle at cold,warm, and AC operation settings. It's possible that you're stalling due to insufficient idle speed setting on the TPS.

Most common cause of stalling for Lincolns in that era is the TPS (Throttle Position Sensor). It regulates fuel mixture, idle speed etc. A bad TPS will usually act up in one of two ways:

1. When cold, car continually stalls
2. When warm, car stalls when slowing down (especially if AC is on)

As far as valve cover oil leak, it's a problem that should be addressed to keep oil from fouling your spark plugs but highly unlikely to be the cause of your stalling problem. Hope this answers your question. All the best.
Greg

this is a dirty idle air control valve, clean it using the following procedure.
Here is the common cause of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake

this may be the cause, try it and see if it helps, it is a very common cause of problems like yours.
Here is the most common cause of surges and stalls and low idle rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Change/thoroughly clean the idle control solenoid. It may be sticking and causing rough idling.
Cleaning it is unlikely to be more than a short-term solution.