I have a 2001 dodge durango with an issue i'm trying to figure out. It has the 4.7L and 185,000 on the odometer. Heres the issue. It idles fine then when i'm at a stop light and go to take off it seems to have no power. If i press harder on the gas the rpms go up but it doesn't go any faster or anything. It'll do this up until about 30 mph then there will be a huge puff of black smoke and it will just take off. I'm just wondering where to start figuring out the problem.

 

how is it shifting? it sounds to me like the transmission is slipping in first gear,

and the black smoke isnt explained by that, but it could be unrelated, or it could be an emissions problem (black smoke is usually a sign of running rich) which would point to O2 sensor, but get the first symptom taken care of as it might just be the engine catching up with the fuel being dumped in while its working through the slipping gears.

 

could be unrelated, but is your cat factory? with that many miles im sure their some carbon built up in their so that could possibly be your issue.

But it does also kinda sound like first gear is sliping though.