5.4 Triton Engine Stumbles
 

I bought a 1999 E-250 with 141000 miles on it. The engine will sometime stumble at between 55-60mph. When it is stumbling I can accelerate hard and stumble goes away. I changed plugs,spark plug boots,fuel filter,air filter,and cleaner MAP sensor just as routine maintenance. The check engine light has not gone on so I do not think it has thrown any codes. Anyone know what could cause the engine to stumble? Thanks

Well, it would be a lot of guessing without codes. Since you changed boots, I would next guess a COP. However there is no easy way to test a COP.

Next time, let it stumble for a while. Maybe then it will throw a code. You are correct that there is no code if the Service Engine Soon light is not on.

Another easy clean is the MAF sensor.

Sprak plug blow bye
 

I have a ford 2000 f 250 i have found the same thing going on but on cylinders five and six changed all coil packs and plugs. i pulled the boot and i found a small order fuel and a rust discoloration (brownish in color). I beliave from smelling and looking that the threads are not tight causeing a blow through on two of the cylinders. This happend once before and i helix coil replacement and the code cleared. And never had a problem again with that coil i gonna do this to cyl 5 & 6 and see if it makes the truck run smother again. i mesured voltage on all good cylinders then macthed to bad cylinders and all the same voltage. I was testing for manifold gasket to have an air leak so i was spraying carb cleaner and listen to hear the engin reave nothing happened so investigated and found to beleaive it is the threads in the alumninum gasket. I will post my result on this.

Is this EGR equipped? If so, check the rubber hose that goes from the EGR to Intake (just in front to of the throttle body). I was having the same issue with no codes being thrown. Drove me crazy until I realized how worn the hose was. I just replaced the hose and it has ran great since. Just as a precaution, I would change the plugs again as well. You could have very easily fouled a few of the plugs out with it running this way.

same thing on my 05 f-250 5.4 triton
 

mine does exactly the same thing, starts misfiring and running erratic at 50-60 miles per hour, stomp it and it quits for a half hour or so and goes right back at it..is this a common problem with the truck or the 5.4 diesel sounding gas engine...it pecks also, has 141,000 on it....

Your issues sound just like what I had going on. Does this only happen when the vehicle is warmed up and/or on warmer days. I had these problems towards the end of the summer and then they disappeared when the temp dropped down into the 30s or so. We had a crazy day when the temp in Cheyenne reached around 60 and I started having the problems again. Once I replaced that EGR hose and plugs (fouled 3 of them by driving with the problem and taking it on the highway), .....no issues

I am sure that all vehicles have EGR, its part of the law for emmisions.:-banghead