I have a 2003 s-type 3.0 Have had a major ordeal with Bank one lean misfires. I have read just about everything and done everything to fix this problem from new timing chains, new injectors, new coils, new plugs with no cure. Then I read about the oil in the intake can cause this and I had notice a fair amount of oil in and around the intake the last time that I had it off. So after talking to a fellow at work he began telling me how a lot of the newer cars have this problem and what I can do about it. And that is to add a catch can on the pcv valve line to catch the oil. No more misfires I don’t know if this will fix all of you guys misfires but it sure fixed mine. You can order these from amazon $20 to $200 I got the cheapest one. Just thought I would throw this out there

 

Very interesting! Please post pics of the installation, and a link to Amazon or other vendor.

 

Which exact codes were you getting?

Also, what were the LTFTs as usually checked (idle & 2500)?

 

You know funny you ask about the fuel trim my short term and long term were bounding around the same for bank 1 but at idle bank 2 short term would be 0.02 to 0.06 plus or minus but the long term will be 14% that has been a strange one. The codes would be 301,303,305 and I’m not sure of the random misfire code off the top of my head

 

I will post pictures when the car comes back home next week my wife is away with it right now and as far as the link just do a search on amazon for catch can

 

Im about to pull my supercharger off to replace a leaky coolant line. I guess itll be a good time to de-oil the heat exchangers and blower....

 

So... those being part of the answer I can really only ask again: what were the LTFTs as usually checked (idle & 2500)? Note: parked, fully hot engine.

As yet we don't know if you even have any air leaks.

 

Those were the fuel trims but I tried everything thinking that it was a leak from using carb cleaner and even used a propane bottle there were no vacuum leaks. I have to say it was definitely a oil problem. But when the car comes home I will tell you the exact fuel trims

 

The code for random misfires is P0300. If the car can identify the cylinder then the last number will be the cylinder that is misfiring.
So you had cylinders 1,3 and 5 misfiring. They are all on the same side of the engine.

Now I did not have the V6 but there is a number of items that regularly go bad on that engine. All of them not too expensive but does require the intake to be removed. So it's best to do ALL the repairs at one time.
If it was my car I would include all new coils and plugs unless they are pretty recent. Vacuum leaks, IMT O-rings, intake gaskets and bad vacuum elbows are just a given.
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Oops, I missed this comment when originally posted. How were you checking for leaks? Were you watching the idle speed? Or were you watching the short term fuel trims?

The computer tries its best to maintain a steady idle speed. Even if you sprayed carb cleaner or propane directly into a vacuum leak, the RPM will stay constant. The short term fuel trims will react, but not the idle speed.