I have a 2008 Dodge Nitro about 190,000 miles on it I bought it about 3 years ago with 140,000 miles. At about 145,000 the engine was replaced under warranty because of knocking. About 6 months ago problems started. It would start right up and still does currently. However, sometimes when you push the gas would pick up speed very slowly and not go above 20 mph. The engine would stumble. If you shut it off and restart, it would work perfectly.

Once in a great while maybe once a month it wouldn't start and the lightning bolt would appear on the dash. I would wait about 30 seconds and it would start right up. I took it to a garage and they said just a bad vacuum hose. They replaced it and it worked great for 2-3 days then it was back. I would see a lighting bolt appear on the dash sometimes when it would happen. I change the throttle body and did a relearn. It seemed to work for about 2 weeks and it was back.

On the way home from work one night it just started to slow down going up hill like the auto tranny is slipping. I manually down shifted for more power and after another 1 or 2 minutes it lost power in that gear. By this time I was up the hill and coasted down the other side. I got home the rest of the way but at reduced speed and in 2nd gear. I checked the fluid and it was not burnt and full. I tried to drive it the next day and it barely went 10 mph.

Where do I start? I don't think it is the tranny. I tried to run codes however the battery died from sitting and erased all codes. I have started it and let it warm up and get no codes as of a week ago. I was going to try to run it until it warms up again and check codes but it may not work. Any help you can give I would greatly appreciate! Thanks.