The 5.8 in my F350 stutters and hesitates quite bad between when it is started cold and it is fully warmed up. It starts and runs cold fine and when it is fully warmed up it runs fine. Somewhere in between it will hesitate and stutter. When it is doing this if I push the accelerator down it will clear up and take off, but can't hold the throttle like that around town. It does it at idle and cruise. Has only stalled on me once. Usually just stutters along until it warms up all the way. I get an occasional CEL for a code 172 I think. I will have to double check the code number. The CEL is not on all the time. It comes and goes and does not seem to coordinate with the stuttering. Wondering if anyone would have an idea where to start to fix this?

Steve

 

It sounds like the plunger in the EGR valve Is sticking and not fully closing, allowing for exhaust gases to be drawn into the intake manifold. Remove the EGR and clean the plunger well. Could be just carbon buildup causing it stick open and not fully seating. Don't use Carburetor cleaner on the diaphragm of the EGR as it can damage the rubber. You can use it to clean the seat and valve part though.

 

Not saying it isn't bad but I replaced the egr valve over the summer. I don't think my old one was bad and I kept it just in case. I will pull it and check it and though when I get a minute.

 

I've seen NEW go bad too. The same goes for these high dollar EGR valves. I bought mine from FOMOCO and all has been well.