Engine Stumbling or Missing at times

[Blakers]

The engine in my 03 stumbles or misses now and then, but other times runs smoothly. It's most noticeable at idle as it shakes the truck enough to make it uncomfortable to do paperwork while sitting at one of my gas wells. It's usually very noticeable at the exhaust sound too. No little puffs of smoke like a drippy injector. Sometimes it smooths out at higher rpm, but sometimes it doesn't.



I don't think it is a total fuel loss to one particular cylinder as it still has power - in fact, I don't notice any perceivable power loss. Today I checked the exhaust manifold ports close to the head with a heat gun and they are all the same.



The truck had this problem a couple years ago and it mostly went away on its own, then started getting bad again recently. It seems like it runs better and smoother after pulling a trailer for a couple hundred miles or so.



I use Lucas injector cleaner now and then, but I don't think it really does much. Not sure if this is an injector problem or not, and if it is, is it an electrical problem or mechanical problem?



Thanks,

Blake

 

[Blakers]

After running a strong dose of injector cleaner, my engine seems to be running smoother and not stumbling. Hopefully it will stay that way. Since it runs better after pulling a load, my thought is that this problem may be caused by too much idling carboning up the injector tips.

I'm still open to other ideas though.