Got a 2004 dodge dakota 4 door , 4 wheel drive... got the P0300, 301, 302 a few days ago.. so checked it out and said plugs miss firing, so replaced the plugs... they all looked good except one, was burned up a lot more.... large gap.... so replaced with new platinum plugs. was running much better, no codes... this morning went out and started the truck, about half an engine turn stumbled and then started and was acting like it was missing on one cylinder... and also a popping sound ... no power afraid to drive it down the street ..... no codes showing up on my computer so far, but did clear the codes after plug install....

took off the positive battery cable after plug insertion for about 10 minutes
added some sea foam to a full tank of gas
check all the connections, non loose, looked the other night for any light
shows under the hood and none..

PS truck has 202,000 on it and has had no problems

So anyone got any idea what this might be? bad coil pack? bad plug?

 

Welcome to the forum Anthony.

Which engine? You said coil pack so I'm guessing the 4.7 or 3.7.

 

yes sorry 3.7

UPDATE: Number 4 spark plug previously was eaten up large gap... so I opted to replace the coil packs... started it up took out the new plugs to check to see how they were firing, number 4 was not firing, lots of raw gas and soot... re-installed the new coil packs, took the battery cable off and then reinstalled.. started up good, was smooth for about 30 seconds and then started missing again and popping in the intake.... took some starting fluid and sprayed around the intake looking for leaks... no leaks.... took it down the road, no power, popping like crazy... thanks

 

Check the compression. You might also want to pull the rocker cover and make sure everythings in place. The 3.7 and 4.7 can drop valve seats.

 

Thanks for all the info... I took it to a local shop.... on the 3 mile drive there it was popping into the intake and could feel it in the gas pedal... no power at all...

they didnt do a compression test, but said they could smell hydro carbons in the radiator... which sounds like a blown head gasket... they told me they really didnt want to do the head gaskets as they dont know what else might be wrong and was pushing me to put in a used engine... so 1500 for new head gaskets or 3000+ labor for a used motor.... I am getting a second opinion in the next couple days

 

If it's popping into the intake then you have a timing/cam issue. Do what Dan said, pop the covers with the engine cold and make the the valvetrain is still in place. Run a compression test and see if you've got a bent valve or dropped/burned seat.

 

Both these engines have problems with rocker arms popping out and becoming useless you can pop them back in remove the valve covers and inspect.

 

You can run a chemical test on the HG for about six bucks, which is the cost of the blue solution. You rent the tester from any auto part store and they refund when you bring it back.