I'm trying to fix a 98 Expedition 5.4L. The thing is running very rough & is missing. I had the plugs replaced made no difference, so I assume it's a coil problem. Only codes it has thrown is P0401 (exhaust gas recirculation flow insuff detected) Any way to tell what cyc. might be the problem, or could it be something else? it has 105k on the motor & I dont know the history as it is not mine

 

hmmm.....insufficient EGR flow makes me think the ports are clogged....check out this thread:

https://www.f150online.com/forums/sh...hreadid=179514

 

Why not service the engine code first then see what you have?

 

turned out to be a coil...