2004 Ford Explorer XLS sporadic misfire on all cylinders

[Kentucky Reign]

Please someone help! It only does this at Idle. My mechanic has checked/changed fuel trim, plugs, coil pack, wires, timing chain, fuel pressure, fuel filter, etc..the basic stuff you would think of. I took it to the dealer today and had the PCM flashed with the latest software as he thought that may help. It didnt. There are no codes, I've only noticed because I'm in the car 7 hrs a day driving and noticed it shaking more than usual at red lights. I'm thinkiing maybe the PCM may be going but I'd like some other opinions. It was replaced 8 years ago right after it was bought. I have no other idea what it may be. Crankshaft sensor? Cam Sensor? This particular model doesn't have an IAC. I dont know but I am stumped

 

[pet575]

Might be as simple as a vacuum leak before you go getting into timing chains, cam/crankshaft sensors, etc. Have you had someone check it out by spraying water or brake fluid on the vacuum lines with it running to see if that changes anything?

 

[rmcknight]

you have the 4.0 right? if you do then its possibly the air intake manifold lower seals. not a job for the technically challenged though...

have a good read of this:
http://www.explorerforum.com/forums/showthread.php?t=335049&highlight=intake+seals