The Nissan Path

Need help with this issue....
It is a 2003 Nissan pathfinder LE 126,000 miles
Lately driving the vehicle i will feel a slight thunk, then the 4wd idiot light comes on the dash and vehicle stalls. This has happened at slow speeds and during higher speeds. If it does not stall its because the gas peddle was depressed. Restarting is difficult, usually takes 3 to 4 times cranking with applying gas peddle.
Vehicle is all stock, no mods. It does a a evap code that always comes on. We have narrowed it down to replacing the evap canister, holding off for funds.
Any help would be great.

Thanks

You'll need to get the codes pulled for the 4WD system. I believe there's a manual method to get them. Downloads of the factory service manual are available from several sources if you don't have one that outline the code retrieval method.