Check engine light - engine miss

These problems can be very difficult to solve. Have you considered taking it to a dealer? They can be expensive, but if they may have dealt with this problem on these Navigators before, and 2 weeks is way too long to have it in a shop for a problem. You can try this place: http://repairpal.com/directory/122898-mullinax+ford+east or here is an independent shop in your area too: http://repairpal.com/directory/266450-legend+auto+truck that I can recommend.

i had a similar problem and nobody could identify the problem. spoke with a friend who was an engineer at ford and we found that the valve spring broke causing the piston to drop and bend. had to take it to a head specialist. i was getting a miss fire code for this.

I had a similar issue with another Ford product and suffered with it for a year or so because no one could find the issue. I tried every part you could think of and it would get better for a little bit but then right back to this issue within a day or so. I finally broke down and put it in the shop. The intake was clogged due to the EGR gases and was causing my misfires. they wanted almost $600 for fix and I was able to complete for under $100. I was told this was a result of a leak in the EGR system. This might not be the same but anything is worth a try and it was just experience of the tech that told him this was an issue and then he did the correct test to verify. We normally check each part and not normally clogged pathways inside the engine itself.