Been having this issue for months now. Truck keeps getting worse and worse. Started it today and ran it came home left it running and sure enough its missing like mad. at idle, sounds like it has a damn cam in it with black smoke out the exhaust a little bit. I can merge onto the interstate or get on the gas and the check engine lights flashes nonstop them finally stays on. code says random cylinder misfire and then list several cylinders. Plugs are ngk about 4 months old, new cap and rotor button, msd wires, msd coil, fuel pump was replaced in 09 with chrysler unit. Last winter i replaced the upper/lower intake gaskets. coolant level stays full so its not a head gasket leak. o2 sensors were replaced 3 years ago with bosch ones. I have cleaned,checked,and determined that all grounds are hooked up correctly. Im stumped.......

 

misfires can be a pain cause there are so many things that can cause them, 1st make sure you havent got a pug wire touching exhast some where, Its getting cold now and moisture can cause havok, check cap and rotor again, If yoy can get ahold of scanner, I have seen o2 sensor really mess up an engine causing them to run rich and miss. Not saying thats it but i would really love to see if they are working right.

 

Have you checked compression?

My 4.7 was missing so bad it would barely idle (and often died at idle). I was getting misfire codes that moved around some.

It had dropped a valve seat, and it was holding an intake valve open. So it was backfiring into the intake manifold (which I assume was disrupting the other cylinders).

 

I had similar problems with my '97 3.9. After replacing most all the sensors, the fuel pump, Ecu, plugs, distributor cap and rotor, the problem still existed. I finally cured my truck's problem by cleaning the fuel injectors. The truck purrs like a kitten now. Good luck, I know how frustrating this misfire can be.

 

Havent checked compression due to the truck running like a top above 500 rpm. Fuel injectors were cleaned when i did the intake gaskets plus with the way i drive.....lets just say they are clean from the amount of fuel i go threw.

 

Those MSD coils (that look like a factory dodge coil) are known to go out. I went through 3 of them within 3 months. I would swap it out with a factory one see how that works out.

I would also double check and make sure the hold down nut for the distributor has not been vibrated loose. This can throw off your fuel sync which then requires an DRBII scanning unit (most NTBs and shops including the dealer own them) your fuel sync will need to be set at/around 0 (some people say +2 is the sweet spot) but dodge calls for 0.

This can also be a PCM problem if you have every power washed your engine bay and not covered up the PCM you can short it out. The flashing CEL is what makes me believe this might be your problem as the same thing happened to me when my PCM took a **** and gave me muti injector codes.

If you have been driving the truck like this for awhile (2 months OMG) yeah those o2 sensors and plugs are gone. Black smoke = unburnt fuel and/or oil.

This would need to be checked with a compression test to make sure the fuel you been flooding into the cylinders didn't wash out the rings. If the compression is low, add a few drops of oil into the cylinder and do the test again if the psi rises your rings are shot and will require a rebuild.

Stock idle RPM is around ~680. So technically your truck should be running fine if it runs "top" over 500rpm. The reason why the rpms are dropping is the misfires at idle.

I can bet you your plugs, and o2 sensors are trashed. I went through 3 sets in 1 week diagnosing my problems on the 01 after the rebuild. Damn PCM decided to take a crap right in the middle of me getting her tuned. After doing all the cheap stuff first, it came down to the PCM.

GL fixing it.

 

Thanks for the reply. Im using a msd coil but its the blaster 2 coil that is supposed to project close to 50,000 volts. Its a cylindrical unit and shaped nothing like the stock dodge coil. Its good and like stated all plugs look excatly the same, good color, no sign of anything un burnt. How can you check the pcm?