5W-30 is fine for the 5.4L. Change your plugs, they are past due at this point. Watch the videos on it by FordTechMakuloco and also look up the tsb. With higher mileage on the original set they are prone to breakage without the proper steps.
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Huh, well that's not confusing then, lol. I too was very much under the impression that even the dealer would have put LV in there instead of SP because SP had been phased out. At this point I'm not going to do a system flush; if 6 quarts of fresh LV made very little difference I have no reason to believe that doing a full flush with SP would all of a sudden fix the issue when SP and LV are apparently so similar as to be cross compatible (if even only for a while).
I ordered a tube of the shudder guard. I put that stuff in a Yukon once that had a slip and it went another year without slipping again before I sold it, so it certainly works. I did a search for "expedition" under the Amazon reviews and it pulled a bunch of reviews for how well it worked on the 2nd gen Expeditions, but only one 3rd gen was mentioned. That does give me hope however.
The problem isn't currently bad enough that I'm willing to spend much money on it... I just let it run for 30 seconds when it's overnight cold before putting it in gear and it's fine. The slips are minor and relative to when I first felt it a week ago, have not gotten worse; in fact they may be a bit better since putting in the LV. Fingers crossed.
I will certainly follow up after I put in the friction modifier.
Thanks all.