Random engine stumble

[Gr8bawana]

1997 5.9 gas engine. Just replaced spark plugs, wires, ignition coil and crank position sensor. Engine starts right up and runs smoothly. After a few minutes it kind of stumbles like it wants to die but does not. Then runs smooth again for a few minutes and stumbles again.
I'm stumped at what could cause this because it runs other than the intermittent stumbling. Any ideas?

 

[Fast69Mopar]

1997 5.9 gas engine. Just replaced spark plugs, wires, ignition coil and crank position sensor. Engine starts right up and runs smoothly. After a few minutes it kind of stumbles like it wants to die but does not. Then runs smooth again for a few minutes and stumbles again.
I'm stumped at what could cause this because it runs other than the intermittent stumbling. Any ideas?

The first thing I would check would be fuel pressure. Then, get a scan tool connected and look at the misfire monitor and the adaptive memory to see what is going on.

 

[Gr8bawana]

OK so we changed out the fuel pump and still has the random stumble. The frequency of the stumble does not change with rpm, it is truly random.
I don't have a scanner just a code reader and there are no codes.
Is it possible I got a bad crank position sensor? The truck runs perfectly smooth other than the stumble.

 

[Gr8bawana]

Update-I replaced the ignition coil pick-up inside the distributor and I thought I had finally fixed the problem. after the truck got up to operating temp the stumble came back. It died after a few more minutes and wouldn't start back up.
It did finally throw code PO340 camshaft position sensor which is the ignition coil pick-up in this truck.
This morning the truck started right up like nothing is wrong and after a few minutes the stumble comes back intermittently. Gonna try a better ignition coil pick-up than the one I got at auto-zone.

 

[Dodge 1500 4X4]

You should buy nothing but O.E.M ignition parts and sensors.

 

[Gr8bawana]

I did get a P-1391 code this morning. Intermittent loss of signal to CMP or CPK signal. Truck seems to be running smoothly with very little stumble.
Got 2 new sensors ordered and I'm going to check all connections and grounds.

 

[scrounge]

I agree about buying a quality sensor, though I'm not adamant about OEM: Standard makes good ones, and RockAuto stocks them (you might have to use the term distributor pickup for cam sensor).

What you describe seems like a cam sensor problem. I was told that the crank sensor can also cause it, but a bad crank sensor is more likely to make it stall, while a bad cam sensor gives it sporadic hiccups. If you've not replaced a crank sensor, I recommend jacking it up and removing the passenger-side front tire for an easier look at where the bolts are. On mine, a 1/2-inch socket was a better fit than a 13-mm; I used that for removal, and a 1/4-inch Allen wrench socket for installation.

One test for a bad crank sensor is, when it's idling, tap it lightly with a wood dowel or the plastic end of a screwdriver. If that makes it stall, your crank sensor is bad.

 

[Gr8bawana]

Well all the sensors have been replaced and we thought it was all good to go. It has finally thrown a code for crankshaft position sensor and code for random loss of signal which cleared by themselves.
Truck was running perfectly for about 5 minutes then the stumble returned, again sporadically and randomly. My son drove the truck around and it was good except for the stumble, no stalling or sputtering. The next day the truck would not start. 2 days later I went out and it started right up now showing a code for camshaft position sensor which we replaced.
Now I'm thinking it may be the PCM because first it wouldn't start and then starts 2 days later when nothing has changed.
Got a PCM ordered and if this doesn't fix it I'm out of ideas.