Hey guys I’m new here. I have a ‘99 dodge Dakota. I’ve had this problem before and out cause the muffler to blow out because the cat was stopped up. But there’sa brand new cat and muffler on so I’m baffled at this point. There are new spark plugs as well just not new wires. It’s wanting to misfire almost it’s sputtering and jumping really bad when it hits roughly anywhere from about 35 mph to 60 mph. And only getting worse. The last time it did this it threw an oxygen sensor code. Everything I keep reading says plugs and sensors and wires. My boyfriend is a mechanic and he thinks it’s the cat getting stopped up again. Any advice at this point will help. And if it could be the cat what is causing it to stop up so bad. It’s been roughly a month and a half almost two months since the new cat was put on. Yeah

 

What engine/trans in your truck?

 

3.9l v6

 

On the V-8's, your symptoms might be caused by a blown plenum gasket. The intake manifold is two piece, and the gasket between the steel pan, and the aluminum manifold likes to blow out. This generally results in oil getting into the intake, and then your engine burns it. That really isn't good for O2 sensors, or catalytic converters..... The six uses the same manifold design, but, I don't know if the issue is as prevalent as it is on the 8's. Can foul plugs fairly quickly as well. If that's not the case, I would take a look at the distributor cap/rotor, see what kind of shape they are in.

 

Well we cleaned the cat out and you can see through it. We do have a bottle of sea foam running through it right now. We finally got a check engine light. We’re about to throw the computer on it. Update: we got the code p1391 loss of crank or cam sensor.

 

That'll certainly make it sputter. Trouble is, you pretty much need an oscilloscope to test the sensors, and see which one is the actual problem..... If you elect to replace either one, use ONLY genuine mopar sensors. These trucks are extremely picky, and simply don't like the aftermarket sensors in critical locations. (cam and crank being right at the top of the list) May also just be a poor connection somewhere..... so, check the connectors for the sensors, and also the connectors at the PCM.

 

So it has gotten worse. It died on me earlier today on my way to work. And now it’s wanting to stutter and jump around 10 mph and when i hit the acceleration it isn’t actually wanting to go I basically have to floor it to get to go. But after that one time of having to do it it didn’t do it again. I’m really just not understanding this.

 

Check the connections for the two sensors.......

 

We’re replacing those today. But the weirdest part. On the Drive home. It didn’t do it once

 

That's just the nature of electrical issues. They tend to be weird and strange. Makes 'em fun to find.