I have a 96 Dodge Ram 1500 4X4 with the 5.2. Truck was running great, however suddenly started running very rough. It runs like it is missing on 2-3 cylinders.

Symptoms:
Running very rough at start up
Won't idle on it's own, will run with throttle input (not great though).
Runs better the higher the rpms go.
Raw gas smell from exhaust
Plugs fouled upon removal and unburned gas on all plugs,
All cylinders firing, but 1 & 8 seem colder when feeling on exhaust manifolds than others.
Good spark to end of distributor wire
Good spark to end of spark plug wires - firing about 1 x second on cranking for all cylinders (question firing frequency?).

Checked so far:
Crankshaft Position Sensor replaced - New
Camshaft Position Sensor replaced - Spare
Manifold Pressure Sensor replaced - New
Throttle Position Sensor, checked 5.10v source, checked ground, reference signal voltage responding with throttle change, 0.36v closed, 3.75v wide open
Distributor Sync - tried adjusting using volt meter, moved to either side of 5v to 0v fall with no change (don't have a scan tool to check sync through ECU)
Fuel Pressure ~ 45 psi and holds well
Fuel Pump and Pressure Regulator/Filter less than 6 months old
Injectors 14.7-15.0 ohms
Oxygen Sensors less than 6 months old
Gas looks good, no water found
ECU - Tried Spare, but might not be good, may grab another
12v to coil
New Ignition Coil
Distributor cap and button ~ 6 months old
Sparkplugs ~ 6 months old

Having hard time determining if this is a fueling issue or ignition issue, or both.
Going to try to clean plugs, unplug injectors and run of just carb cleaner, to see if I runs better.

Open to ideas, thoughts, and trouble shooting suggestions.

 

What brand O2 sensors? Other sensors brand? These trucks really don't like aftermarket sensors in critical locations. Cam and crank sensor are right at the top of the list.

Given that its running pig rich, I think first I would disconnect the front O2 sensor, and see if anything changes. If not, need to plug in with a scanner that can read live data, and see what the PCM thinks engine temp is. There is a separate sensor for the PCM, so the gauge reading correct is NOT a good indicator.

 

Not only engine temp but also intake air temp, short & long term fuel trims and O2 sensor readings might help to track this down.

 

Crankshaft Position Sensor is MasterPro
Camshaft Position Sensor is Mopar (I believe, bought long time ago)
O2 Sensors are NTK

I forgot a few more checks I had completed:
ECT - ohm's checked fine (~14.1k) and computer was reading correctly for outside temp and cold coolant
IAT - ohm's checked fine (~13.5k) and computer was reading correctly for outside temp
Compression Check, all cylinders between 175-185psi, cold, dry, (cylinder #2 190psi)
Tried different ASD relay
Verified 12v to PCM

I will try disconnecting the front O2 sensor to see if there is any change in running.
I disconnected the battery to reset the PCM so I don't have long term fuel trim data. I will try to get it running long enough to see what short term fuel trim value is doing.

I am looking at getting my hands on a "professional" diagnostic tool to read more PIDs, unfortunately readable data and frequency of live data refresh is limited in Torque App.

 

I bet the crank sensor is your issue. I had the same thing and it was the generic sensor. I replaced with a MoPar sensor and it went away

 

Update on Issue:

Sorry for the long pause, was in the process of fixing up a house, selling, purchasing a new house and moving.

Turns out it was two issues, the main issue was the number 1 cylinder exhaust valve spring had broken. It was sometimes sealing creating compression but mostly not. After fixing that issue (new heads), the 2nd issue was the generic store bought crank position sensor. When it would get hot, it would starting providing intermittent signal to the PCM resulting in spark loss to the point of not being able to run. Purchased a new Mopar sensor and issue is resolved. Now just working on the computer tuned.

A thank you to everyone that replied and offered assistance.