[BIGDave072]

Quick background: Check engine light has been on for a while -- At least two years (I know, I shouldn't have let it go for so long). Fault code always came back as a very small Evaporative Emission Leak but tightening the gas cap never kept the check engine light away. The truck ran fine but gas mileage was normally around 12mpg (all city driving in a city where there seems to be a red light every 100 yards) which always seemed on the low end of the 5.7L Hemi's range.

Today I was driving home for lunch and, after driving about 10 miles, there was a 500 yard stretch that the engine felt like it was running really rough, kind of choppy like it was misfiring. I pulled into a parking lot and as soon as I was off the road the engine died. I was able to restart it but it idled extremely rough and would die if I didn't consistently rev the engine to a higher RPM.

My first thought was that I'd gotten some bad gas. I'd filled up the day before from less than a gallon left in the tank (7 miles until empty on the computer) to a full tank. But my wife and I went Christmas shopping later that night and drove all over town looking for a Wii Fit (nine stores with no luck!) and I had to drive to work the next morning and then to a few appointments. So all together I'd gone through nearly a quarter of a tank before the problems started. Just to be safe I put a bottle of Heat into the tank hoping that might clear things up but that hasn't made a difference so far.

These are the fault codes that read on the dash:

P0300 - Random/Multiple Cylinder Misfire Detected
I think this only came up because the engine idled so rough (Maybe from not getting the right mixture of gas/02?)

P0442 - Evaporative Emission Control Leak Detected (Small Leak)
I think this code is new.

P0456 - Evaporative Emission Control System Leak Detected (Very Small Leak)
This is the code I'd traditionally gotten in the past and I'd always read it was likely the cause of a loose or bad gas cap.

It was cold and rainy today so I wasn't really able to check any of the Evap. System for cracked hoses or leaks. The reason I'm posting on here is because it seems like a very small to small leak in the Evap. System shouldn't keep the truck from running at all.

Do you think it's possible the mixture of bad gas and an evap leak could be the cause of the problem or should I just stick with what the fault codes are telling me? I'm open to any input or suggestions you can think of. Is there something more I should try besides heat to make sure it's not bad gas before I spend a lot of time checking every inch of the evap system?

I know it's getting late but hopefully someone is around who can help because I really need my truck back up and running and I need the fix to be as cheap as possible (these things always happen at the perfectly worst times don't they?).

Thanks in advance for any help you have to offer,
Dave