I have a 2000 dodge dakota sport 3.9L! I had a new engine put in the truck and when I got it back I noticed that one of vacuum lines that run into the valve cover had been broke off. I started smelling fuel very bad as if it was getting flooded and I started getting very bad gas mileage. I still can't figure out why it is like that my check engine light is on as well and it will not shift into overdrive. Runs at about 2200 or 2300 rpm all the time. Anyone have the answer for me

. Check for codes.

. Check all under hood and under dash fuses with a test light or multimeter.

I would suggest fixing that broken line and also check all of your vacume lines for leaks as they do have a hand in controlling the transmission