mysterious p0300 misfire

[jake321]

2004 dodge ram 1500 5.7l upgrades include K&N cold air intake, 37+13.50+18 cooper stt pro tires, magnaflow exhaust, bullydog programmer, helwig sway bar, fabtech 4bar torsion kit, 6inch skyjacker lift on pro comp nitrogen shocks, 4inch level kit . issues im having are at only 80 to 100km the vehicle stutters and chugs/bogs but when gas is applied or taken away then the problem stops but anything under 80 or 100km or even above that it doesn't have an issue only when the vehicle is cruising between the 80/100 speed and rpm of 1500 it chugs also when towhaul is activated the problem deceases but is just at 75kmh,my fuel economy is horrible and also it will throw a code p0300 random multiple misfire. I've just changed all o2 sensor's all plugs changed to factory gapped plugs coil and wires are in perfect condition bullydog is set to proper settings vacuum tested fine... idles at normal idle all injectors are tested and run at proper ohms and they tick under a stetha scope we had it on the ob2 scanner at a transmission shop I took them for a drive and showed them the issue they said all cylinders are firing properly and have no issues also the torque converter is engaging properly so he says it highly unlikely its a transmission problem (Belleville transmission) and the engine to there high end scanner is running properly and showing no problems I can clear the p0300 code bye unhooking the battery but after 20 minutes or so of driving the code comes back when driving below 80kmh I have all the power in the world.... from a stop and go I have all the power I could want also but when cruising between the 80 to 100 kmh mark the vehicle misfires and chugs ive literally stumped and confused 6 shops in my town and even my own dodge dealership is lost for words so if anyone could maybe give me some insight im literally at the point I have to give the truck to someone and let them go threw it with every scanner and machine know to man kind which is going to be costly on my part

 

[blackbeautyhemi]

Did you try setting the bullydog back to stock and running it by chance?

 

[jake321]

yes and it still has the misfire even with the bullydog uninstalled

 

[blackbeautyhemi]

Okay just checking cause my buddy had issues with his bullydog making his 08 hemi run like ****.. Uninstalled it and it's been perfectly fine since.

 

[jake321]

ya ive heard of people running into issues with there programmer's before but it just throws my speedometer off and still does it

 

[chefred112]

you may try changing the MAP sensor. Had a fellow local guy have similar symptoms (and to a lesser extent me), swapped out all the sensors and still his truck ran like crap...he then replaced the map sensor and that did the trick...I did the same and I notice that these intermittent symptoms also went away..

 

[Redtruck-VA]

What gears are you running with the 37" tires? You may be just plain bogging in that rpm range.

 

[Dknight]

I know exactly what your talking about, my truck was doing the same. It was ignition breakdown for me, the plugs were worn out. I grabbed some mopar coppers which are champions and it was night and day difference. Remember to gap them! I went with .45

 

[jake321]

misfire problem has been solved. it was due to a wrong setting in my bullydog it was trying to run the engine as a 3.5l at 4000lbs when my truck is obviously 6600lbs and 5.7l hahahhaaha change this and no misfire but the odd thing is I still get the vibration at 80 to 100 km so it was 2 issues making it seem like one mystical problem