Currently battling the dreaded 0442 code, but I'm going *****-to-the-wall this week and doing the Vapor Canister and all the hoses.
However, I don't this problem has to do with that.

Since I've owned this truck, when it's cold or rainy, I'll take it out of gear or put the clutch in and coast and the Tac just drops below 500..the engine hesitates, the headlights dim, but it never actually stalls. A little tap on the gas pedal or coming to a complete stop resolves the problem.
I've done IAC, TPI, Cleaned the Intake, ran several full tanks of Sunoco 93 through it and even some Lucas Fuel Injector Cleaner (I also tried this Red Gunk, can't remember the name, on the suggestion of a friend/mechanic).

The truck is an '03 Dak SQC (5spd) with Mag-Cat and Flowmaster Super10. I would've imagined that would be the problem, but this issue existed before I started modding. I figure I want to do a CAI soon to see if it's a breathing problem, but I'd kinda like to lick this before I do any more modding.

Ideas?

 

Be ware on the hoses. There is one that is formed, 1/2" at one end, 3/4 at the other (I THINK), and in a horseshoe shape.

 

Yeah, that's the molded end at the purge solenoid. We don't know what to do about those... Dodge wants an arm and a leg for them.
But I don't know if the EVAP issue is connected to the Hesitation issue.

 

I was just gonna get an adapter fitting after I find out exactly what size it is...