After driving at Interstate speeds and exiting to the first traffic light at the end of the exit ramp, my '05 XF Ltd. has begun to shudder as if it is going to stall. New tank of gas has not made any difference. What's up with that?
PS: I've recently installed a new MB airbox w/3"d snorkels.

 

When you mean shudder do you mean like at idle it wants to die/not catch itself on deceleration? Does the problem present itself under acceleration? If the car isn't throwing any codes and hasn't done it before it is possible that you just got a tank of bad gas.

Best way to determine if it's gas related is pull the fuel line off the rail and turn the car to on and drain the entire fuel system, including the tank and start over with known good gas

 

I had a problem that sounded very similar to this and when I took it to the dealer they noticed my volts were all over the place. From 9 to 15. They replaced a large portion of wiring and it hasn't come back

 

Yes, the car seems to be on the verge of stalling/dying when I come to a stop. I've noticed it is sometimes sluggish on acceleration from a dead stop. So far as CODES, you, sir, are communicating with an IGNORAMUS when it comes to most auto problems. I do not have a code reader, and I want to avoid the dealership as long as possible. Ergo, no code references to furnish. (Thanks Voyager).
Had filled up from 1/4 tank previously. I always top off the tank to avoid condensation problems. I DID fill it up at the same time the fuel tanker was filling the underground fuel tanks. Something I usually try to avoid.
Sure hope it is not the wiring issue that Voyager experienced.
Guess I'll work my way through the current tank as I have no way of draining a fuel tank with the limited resources I have. Is there an additive that could help with that?
Sorry so many questions, but again, I am chief among Ignorami.

 

If I had this problem I would take off the new air box and put the stock one back into place. This way I would be eliminating one possible problem, however unlikely.
Before doing it I would check to see that the new one fits perfectly. I have not fitted one of these air boxes and wonder if the air box locators have to be adjusted in any way, the rubber seal is still in place and not missing or has a gap.
I am assuming that sometimes it works OK and then does not, am I correct?
If it is leaking air it may be an air mixture problem.

 

Thanks~
My mechanic (former MB mech. now owns own shop) installed it and when I asked about a re-tune, he said it was not needed. I put the larger snorkels on by myself, but they were a simple hook up through the holes where the former supports were on either side of the radiator. I will go out later and look to see that the box is still properly aligned with the intake manifold. You may be right, I will check. Thanks for your advice!

 

My car does that every once in a while. I'll stop at a light and it feels like it doesn't want to idle. It happens no matter what kind of driving I am doing. It has only happened maybe 3 or 4 times. When it happens, I just rev the motor a little, and it's fine.

 

The airbox and snorkels shouldn't require a retune. Make sure the maf is tightened down and is pointed the right way in the intake. If the maf was dropped or shaken hard it could have gone bad. They have a crystal in them that is very sensitive to shock loads and g-forces.

Unless the check engine light on the dash is on, there are no codes to check. If it is on however, most local auto parts stores will pull the codes for free.

I'd put the stock airbox back on and see if the problem still presents itself. If the mb box somehow came off the rubbers slightly that could cAuse the rough running due to a post maf air leak.

 

Well, I went back out and checked the seating of the air box, and it was "high" in the back and slightly off the intake. Must have pushed the front down slightly when attaching the snorkels. Shoved it down, and behold! No more problem! I LOVE THIS FORUM! THANKS MEN! Perhaps I should stay out of the engine bay...