New to the site and thank you in advance for any help and/or ideas.
Here's the issue: On hot and very humid days my 98 Dakota (auto, 3.9, 180K) runs very rough. It starts fine, but when I get a block down the road it loses power, sputters, coughs, even a couple small backfires. Then runs fine! It lasts about 20-30 seconds. I have replaced the plugs, wires, cap, rotor, and just replaced the IAC today. Still does it.... Has not had this problem in rainy weather. Just hot and humid days.
If the truck sits for off for 10 minutes it will do it also. No codes, no check engine light either. Pulling out what little hair I have left! lol
Thank you for any replies.
~Tim

 

It sounds like a cat or the upstream O2 sensor is bad. But that wouldn't change when temps change.

 

Thats the best way to desribe it as the cat is bad. But it goes away right away. I've driven over 100 miles the other day and no problem, other than when I first started off. The humidity is supposed to break tomorrow, so we'll see if it resolves again. It did this 2 weeks ago when we had a high humidity spell...
~Tim