I have a 01 dakota with aprox 120,000 miles. I'm having a misfire when I hit around 10-30 mph. It doesn't happen all the time. maybe like 2 out of 10 times you drive it somewhere. This happens when the engine is cold or warm. This all started out with a failed o2 sensor code, which I replaced, then I got a code for a misfire aprox 3 months later. I believe it was for the 1 and 3 cylinder but don't remember. I brought it to a mechanic and they recommended a tune up which I did. My truck still had a misfire so I bought the truck back and they are have no idea whats causing it now. When you get past 30 mph the truck runs smoothly the rest of the time. I can generally tell its going to misfire when I start the truck because the idle is a bit rough. The idle makes a gargling noise. Anyone have any ideas?

 

This sounds exactly like the problem I'm having and I finally caught it on video. I'm uploading it right now, tell me if its similar

 

It's somewhat similar but mine happens right away. If you hit 30 mph it wont misfire at all and run smoothly.

 

I'm still having the misfire problem so I dropped it off at a dealer. They told me that the number 3 and 5 valves are bad and need to be replaced. To me that doesn't make sense. If it was bad valves, wouldn't the misfire happen more often?

Side note.. They said that they did a compression test and got 30 lbs on the number 3 valve and 110 lbs on the number 5 valve.