Any ideas why I may be stalling out?
Recently bought an 04 3500 5.9L with about 240k miles on it. No dash lights. Since then, I have been stalling out while driving 3-4 times a day. The oil pressure gauge plummets right before and then stalls. Will start right up immediately, which I usually have to do since it will happen when I’m cruising at 30-40mph on a main road with no good pullovers. I’ll make it another 5 miles then same thing will happen. Both batteries are new and strong, all connections are good and strong, has a good ground too. Recently had oil change, no visible oil leak, and dipstick reads full every time I check it.

 

While I generally hate just throwing parts on a vehicle, just in case something sticks to resolve the problem, I would take a wild guess that you may have a bad ignition switch. The switch is not that expensive nor hard to change, so maybe start with that?

Let us know what finally resolved the problem.

 

Have you hooked up a code reader and if so, any codes?

When you say "right before", what do you mean by that? Is it a few seconds, a second, or as the RPM drops during the stall? What is the oil pressure when running normally, and is it usually steady until it drops and stalls?

So far, I'm agreeing with Mexstan on the ignition switch. I changed mine out in the '03 before. No worries with the new part as you reuse your original key cylinder and your original keys.