Just purchased a 2007 2WD V6 Dakota, 133,000 miles. Everything is in very nice shape and it ran just fine the first 160 miles I've had it. This morning, 90 degrees, engine at normal operating temp, been driving for about 30 minutes, stopped at a store for the wife. When I came out it started normally but stumbled slightly when pulling out of the parking lot. The check engine light blinked and then came on steadily. Got up to about 50 MPH and it stumbled again a little more vigorously.
I stopped at the gas station, I was down to just under 1/4 tank, and filled it. Nothing obvious amiss in the engine compartment, oil full, water temp in the normal range. Wound the heck out of it climbing the hill on the way home with no miss or hesitation.
I'm old and have worked on cars for 40 years, but have not invested in one of those computer reader thingies. Have always been able to diagnose with a good ear and a vacuum/compression gage. So how do I interrogate this thing to see what has it upset?

 

Get a code reader they cost about $60.00 and up but worth the cost

 

It's all computers now...get the codes first thing. Some parts stores will scan it for you, but DON'T let them sell you anything until you get a diagnosis.

 

Going over to Autozone today to see if they'll check it with a code reader. The truck ran smoothly for a couple of days and the light went out. Then this morning it acted up again. As I get used to it I'm beginning to suspect a transmission issue. The automatic seems to hunt, uncertain what gear it wants to be in. If I floor it, it will wind all the way up near 6000 RPM without a miss.
Does this have a lock up torque converter?

 

Scanner says I have a misfire condition. Starting on the passenger side at the firewall I began pulling the coil packs and sparkplugs. Center electrode was worn almost to the insulator. Three on the passenger side went OK but the front plug on the driver side is where I ran into trouble. Should have used PB Blaster on the 10mm nuts but I didn't; I snapped the stud holding the coil pack in place flush with the coil pack. I haven't pulled it out yet, but I'm hoping the little stud holding it in place is threaded into the manifold and not pressed in. Anyone run into the same issue? Replace the stud or???

 

Well, I went on to another plug. This time as I backed the 10mm nut out to release the coil pack the stud backed out instead. Then I came to the realization that the intake manifold is plastic; the stud is probably threaded into an insert. It came out to a point where it would turn but not back out completely. The coil pack and stud would move up and down about 1/4" but that was all. I screwed it back into the manifold and that seemed to work. So now my question becomes do I have to remove the intake manifold (and all the "stuff" mounted to it) in order to get the coil packs bolted down? At this point I've replaced four of the six plugs. In light of the condition of the four I pulled out I don't want to leave the two old plugs in place; ultimately I have to replace the two. So, how are the studs retained and where do I go from here?

 

Well, lacking any response, I drilled and tapped the broken stud end for a #4-40 screw and that, with a washer, now retains that coil pack. The #5 coil pack gets attention this weekend. I'll back the stud out to where I can grip it with vice grips and try to back the nut off. If that fails I'll cut it off and use the #4-40 screw solution.
With all but one plug replace the stumble is almost completely cured; it only stumbles a bit climbing a hill under heavy load, so I'm pretty certain I've found the solution.