Chrysler Repair: 2000 300m will turn over but wont start

Question
well im stumped big time!!! my car ran and drove the day this happened. unfortunately i was not driving it when it failed. i have checked or replaced the fallowing; starter(new)spark plugs(new)batt (new)all fuses (none bad) timing (correct) coil packs (firing well)injectors (good) fresh fuel and a can of heat and still no start. like i said it will turn over but will not start. had the codes checked and none were present. i did get a p 1684 code on the odometer,my guide says that the batt has been disconnected in the last 50 starts.this i know. as it turns over there is a squawking noise and it acts like it will start but just wont get there. any help u can offer will b greatly appreciated! in closing my car is a 2000 chrysler 300m w/ the 3.5 high output motor.

Answer
Hi Joe,
A no start with no codes means that it has to be either fuel supply, spark, compression, or mixture.
On the fuel issue: do you hear the fuel pump run for about 1 second when you turn the key to the 'run' position, which would be the normal behavior. Listen for a hum at the fuel tank. It starts running again when you activate the starter but you might not be able to hear that.
It is also possible to chack fuel pressure via a port on the fuel rail where you can attach a pressure gauge, but at least for now do verify that the fuel pump hums.
On the spark, did you verify that a plug is actually firing as you crank it over? By 'coil packs' did you mean the individual spark coils (one mounted on each plug) rather than a "coil pack" which I usually associate with a single multicoil (3) spark unit (pack)?
Compression of course would have to be checked with a compression gauge on one of the cylinders.
Mixture is often the reason for a no start with no codes: specifically the exhaust gas recirculation valve being gummed-up such that it is not closing tightly when the engine is turned off, or while it is decelerating to a stop which then causes a stall. You can remove the valve and examine its interior passageway for signs of plugging up and if the valve stem is accessible you could move that back and forth to be sure it moves freely and that internal spring-action moves the stem to a dead-stop in the closed position. That egr valve would be definitely something to investigate as if it is stuck ajar then the return of the exhaust gas to the intake manifold will definitely thin out the fuel/air ratio too much to allow for good combustion when starting.
Please let me know what you learn.
Please read the PS (below) and respond to it.
Thanks,
Roland