I have a 89 Dakota Sport 3.9. It was my dads truck and he had parked it for three years with no start ups during the 3 year sit. He told me i could have it so i pulled plugs put in a Tspoon of oil in each cyl and turned engine by hand. Was not tight at all. List of all parts replaced before start up. Fuel pump (cleaned fuel tank and purged fuel lines),fuel filter ,both injectors, cap rotor plugs and wires fresh oil and filter. i had a check engine light the code was in reference to a injector. i didnt have it seted properly. check engine light is now off but truck idles rough. The o2 sensor is not connected and coverter removed shortly before truck was parked for the three years and did not cause a issue at that time. i consider myself fairly mechanically inclind but im not sure where to start with diagnosing this idle issue. Not sure if its spark related or fuel. Can anyone give me a good starting point. i have done a fuel pressure test and it was right at suggested pressure. Thanks in advance if anyone can give me some pointers.

 

Both injectors? A 98 should have six.....

What plugs did you put in?

 

fix the o2 sensor then...

first thought was....put a timing light (if you have one) on each plug wire and make sure they are all firing, if not put in fresh plugs, run it for a bit then pull the plugs and smell each one for gas. if any smell like gas then it is not firing correctly. swap wires for that cylinder, swap the plug with a plug that is firing and run it for a bit. yank the plug and see if it smells like gas. if no then new wires may and be bad.

...but after reading it and thinking about what you have done, i will bet you might have a stuck ring or two. go get a small bottle of marvel mystery oil and drop some down each cylinder and let it sit overnite or longer, pull out a quart of oil and replace with hot shots stiction eliminator. the next time you work on it fire it up and let it idle for a bit, 15+ minutes or so, then take it for a spin in neighborhood. if a ring is stuck causing low compression, it should free up and seal better after this.

 

My apologies I had just woke up when I joined the forum. My Dakota is a 89 throttle body injection that's why just two injectors. I will check on the plug for you been a bit since I put them in.

 

OK so now that I realize I have entered the wrong year and wrong forum do I need to switch this thread to 1st gen? Also got some new info. My dad just remembered something on the distributor had broke or cracked he couldnt remember for sure but a friend did a quick fix with JB weld (hate when people do that) anyway I'm going to pull and replace the distributor in the next week or so. I will definitely post the results if still have idiol problems I will do some of the suggested diagnostics you guys recommended and reply with results. Thanks and sorry for the incorrect year I posted!
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I'll move this to 1st gen for ya. Edit the first post to reflect the correct year.

Find out what got patched on the distributor before you pull. Maybe you can just look??