96 F150, 4x4,5.8. I had engine check lite on for a couple years. I finally got around to putting a scanner on it to see what codes it had. It came up with P0401 EGR Insufficient Flow. I know how to check this but have a couple other questions I want to address first. 1) I erased code and it has not came back, have driven it about 200 miles. Does that mean the problem no longer exist? 2) Will this code cause a misfire? I always thought this truck idled a little rough, but I noticed if I hold rpm to about 2000, (in park, no load) it has a miss. I can not feel it while driving down the road.

 

Too much EGR flow can cause a lean condition. The it's possible that the conditions needed to do the system check haven't been met in those 200 miles. I'd test the sensor and pull the EGR valve for carbon buildup.

 

The silicone hoses from the sample pipes on the EGR tube can be brittle and broken. the same sample tubes can be plugged with carbon as well. Carefully check both.

 

Thanks for the replies. I will check these things this week end, if it warms up some!