I have a 2001 Dakota 3.9l v6 4x4 automatic. The issue at hand is while driving at various speeds and maintaining steady speeds. Suddenly the vehicles rpm will not rise unless I stomp on the pedal. If I try to ease my speed it will lug more and if it gets to around 15 or 20 km an hr. it will buck like its stalling. I've changed the plugs and wires. Distributar cap and rotar as well a the coil. Could this be an issue with the catalytic converter. Or with a sensor in the transmission. Or is it a fuel pump and filter issue. Any and all help will b appreciated. I do not have my codes. Just hoping someone has run into this and has fixed it. Thanks, Linton!