Went on a little trip last weekend to grab a set of wheels and tires and it was 2.5 hours up and 2.5 hours back but on the way back the CEL came on but the truck didn't act any different what so ever. I was running cruise at about 70mph when the light came on and I didn't think anything of it really, thought it might have just been the gas cap. Tuesday of last week I was heading over to my garage to dump off the tires and did a WOT run just messing around and the code cleared itself. I got my hands on a code reader this weekend which is how I found out that it was a p0300. Did some research on it last night but only found that when people had this code their truck would run bad or stumble or you could actually hear a miss in it, mine is totally normal which is why I'm a little stumped here.
Could it have been some bad gas or something that threw the code? I know there are numerous things that could do it but with it clearing itself and acting fine, I dont think its anything too serious.

 

If it cleared itself I would not worry about it. May have been some fuel issues hard to say. What all do you have done to your truck?

 

Just a blackbear 93 tune, exhaust and CAI.

I also have a stumble in the mornings, whether is cold or warm out. If i let up on the gas real quick at a low rpm and while being in a high gear, 3rd or 4th, it sort of loads up and jerks a little. I just figured it had something to do with it not being up to temp. Two or three miles down the road its fine. I swear its got an attitude some days.

I may pull the plugs this week just to take a look see.

 

Is your truck a stick?

 

yes sir. nv4500 behind the 6.0

 

please go on, i have similar issues with my truck. hasn't happened recently, but when i hook up a tech II it has a P0300 stored in the memory, not setting a light like it used to

 

Well it happened again, under the same conditions, traveling down the interstate between 70 and 80 mph. Seems like it happens after about 60 or so miles. I haven't actually hooked up a code reader to pull the exact code yet to be positive but I'm willing to bet its going to be the same random misfire p0300. The only other code the truck threw ever was (forget the number) something in regards to the MAF not seeing enough air needed, but that was my fault cause I had a puny little cone filter on it and was running WOT up hill pulling about 8k pounds. What the heck could be causing this p0300? I haven't check plugs or wires for a while but I dont drive the damn thing all that often so I doubt they aren't bad. I also didn't get gas at the same place I did the last time this code showed up and its been a couple hundred miles since then so unless I got two bad tanks at two different locations (different vendors also) i can probably rule that out. Also, the truck doesn't run worse when it throws this code but call me crazy but Its almost as if it runs a little better when its on. BTW, it also cleared itself after the 4th or 5th start up a few days later.

 

Check for a bad coil or a loose injector harness connection at each harness to make sure it's fully connected and not wiggling loose. I had both.