Okay, I have a 2001 Ram 2500 with the 5.9L V8. The truck has been exceptional since i bought it about 6 months ago. It now has around 102,000 miles on it. Just about a week or so ago, I went out, started the truck, it started just as normal, let it warm up a couple of minutes, then went on my way. Starting out, slowly accelerating it had a small miss. When i accelerated harder, the miss disappears. Further on my drive, up to highway speeds of 65, in overdrive, when just coasting, i started noticing a slight shutter and vibration coming from the engine. Check engine light has been on since I bought the truck. The dealer I purchased the vehicle from ran a scan and it was P0442, EVAP system small leak/no flow condition. The truck ran fine since the day I bought it so I didn't worry about doing anything. Now since it has started this, I got it scanned again to find codes, P0442, P0455(EVAP large leak detected), and finally code P0138(circuit condition heated oxygen sensor bank 1 sensor 2). To this day, I have replaced the spark plugs, which the old plugs looked fine, and the O2 sensor that the code said to replace. I cleared the codes by unhooking the battery for 5 minutes and hooking it back up and letting it idle for 5 minutes. No check engine light has came back on but the truck is still suffering from the same symptoms. I have drove 125 miles since resetting the system. Any ideas?

 

Check the wire routing of your spark plug wires. also check cap and rotor for wear and condensation

 

It takes a good long while for evap leak codes to be set. It's a good time to hunt those down and fix 'em because they're likely what's biting you.

 

the miss/stumble at light throttle which disappears at heavy throttle sounds like a vacuum leak.

442/445 evap error might be cause, of the engine running poorly, as these codes are usually caused by split vacuum hoses at the cannister or evap pump. however, i drove mine for well over a year with these same codes and they never affected the way mine ran, probably because they were at the canister, and not affecting normal running.

check your evap hoses, but also check your vac hoses in and around the intake manifold.

sometimes its easier to plug off all vac lines at the manifold, and then add them back one at a time.

https://dodgeforum.com/forum/2nd-gen...-leak-fix.html