I have a 2000 Dodge Durango starts runs idles fine I can drive it but as soon as rpm gets about 3000 it like chokes out and smells like fuel and carbon. Any ideas

I can get the rpm to go up if i manualy put it
in 1st or second on the column and hardly
press on the gas. I recently bought the
durango and dont know much about them. I
have changed all 8 plugs and checked coil
packs. It isnt throwning any codes except
battery voltage temp too high, and it wont
let me clear the code. The orignal problem
with the rpm started after i had put a lucas
oil fuel system cleanier in the gas tank.
Now im just kinda stummped. Any one else
have the same issue? My thoughts were
fuel pump or catalytic converter. But dont
have the money to purchase both and
replace. Plz help its has the 4.7l v8
magnum in it
Scott seifert