sounds like cat

 

If the CEL comes on, there should be a code stored. Sometimes "soft" codes can even be stored without a CEL, but not the other way around. Thats just weird.

Ideas for you to check, off the top of my head:
-Busted plenum gasket
Take off the air cleaner assembly and look into the intake manifold, past the butterflies. Any oil in there? If so, probably a leaking gasket. Very common on our Magnum V8 engines. You can do a search of the forum for more info on that, its been covered lots of times.
-Oxygen Sensor
As someone already said, could be a bad O2 sensor. However, that would usually trigger a trouble code.

Did it start doing this before or after you did the tune-up (wires/plugs/rotor/etc.)?

 

get new cats or hollow them out. My 5.9 is a 2002 but had the same problem it would stall every 3 minutes, ever since I hollowed mine out it’s been running amazing. Give it a try bud

 

11 years later......

 

12 years later. And still no EGR valve on my 98 Ram LA360

 

Unless you put a LA engine in there, its a Magnum engine.

 

Read post #7! (Magnums up to 1995) It's possible the engine was changed with a earlier one(with egr). Actually the egr ports on the LA's where under the carburetor in the intake.

 

My '96 5.9 kegger intake has a place for the EGR to bolt-on to, however, its not used.

 

Yeah, mind did too. There was a plate covering it instead.

 

I think they used up the reaming previous years stock before switching over. My 96 does not have it.