I have a 2001 dakota witha v-6. starts fine and runs fine till you stop. After restart it runs bad and backfires through throtle till you floor it one time. Has to be in drive when you floor it to get it to run right again. Will work if just reved up. Has new upper o2 sensors, new coil, new wires, new plugs, new cap, new rotor and new tps. Any ideas would help. Also now the automatic transmission has started acting up. It wants to start out in second gear. While sitting at a light you can feel it drop into 1st then out again. After starting out it changes gears good and shifts great. Will work fine if pulled down to 1st gear with shift leave but thats really had to shift to 2nd or drive.

 

Welcome to DF
You may have a bad temp sensor if the engine runs good when cold. and the transmission problem maybe the governor solenoid and transducer. I will move your post to the 2nd Gen Dakota section.

 

I had a VERY SIMILAR problem with my motor!! I replaced every sensor on the engine new plugs,wires, cap and still ran horrible/barely idled wouldnt drive without floating the brakes and throttle. My truck has 166,332 on my 3.9L The throttle body had never been cleaned or removed!!! after I removed and thoroughly cleaned the Tb with some B-12 Chemtool and a toothbrush the truck has never ran Better, Try this for your Idle/Backfire problems. As for your tranny if you find the solution let me know, mine is acting up in the same matter as well... Good Luck!!

 

Well I installed a new water temp sensor, cleanded the throttle body and caped the vent on the distributor and have no change. Still acts like its fooding out and back fireing throught the throttle body till you floor it one time. I also noticed that if you put the truck in 2nd gear to start off it works better and the once started shift to drive it work ok then. Not sure what to try next. Hate to spend the money for a map sensor when I have no code for it. I did check all sensors with a volt meter a while back and they all check out ok. Maybe their is no fix. I like the truck but this may be the last Dodge I ever purchase. I can't seem to find any post anywhere that people that have had the same problem have found a fix for it. Seems noboby knows. What to do!

 

May have found problem. I used the old left O2 sensor on the right to try it. It worked it seems the Bosch O2 sensor not any good. Read O2sensor swap and you'll understand. I hope maybe this will help others that have the same problem I have. I also think I found the trans problem but have not purchased the sensor yet to try them. I found a video on this site that showed how to fix. It was from you tube.

 

So you found out it was your O2 senors huh? I guess ill check out that O2 sensor swap thing and maybe learn something new haha. Good Job!!