This morning I wrote the following response to "Keebo" (shown in italic text below). Per the Mopar Online Parts website, the 3.9L and 4.7L use the same upstream O2 sensor (p/n 56041213). So I'm thinking that if you are seeing a P0132 code, the upstream O2 sensor is probably failed on your 4.7L too.
I recently had the exact same drivability issues with my 98 3.9L Dakota at 136K miles. Finally got so bad that it set several cylinder mis-fire codes and P0132 code (O2 Sensor High Volts Bank 1 Sensor 1). Your upstream (before catalytic converter) oxygen sensor is probably failed. The vehicle runs fine cold because it is running in "open loop". When warm, the vehicle changes to "closed loop" control, which uses input from the upstream O2 sensor to control engine fueling. On my scan tool I could see the upstream O2 sensor latched at false full rich (1.0 volt). Then I saw the fuel trims trying to lean out the fueling, which is why the vehicle sputters and backfires when warm. It is literally not getting enough fuel to run properly and make power.
I installed a new upstream O2 sensor, purchased from the local dealer (they are still available thru Mopar). My Dakota runs perfectly now. On my scan tool all is normal now. The O2 sensor voltage switches low and high, which is proper behavior.
Note there are several videos on the internet on how to change an oxygen sensor. I used a map gas torch to heat the bung on the exhaust y-pipe. Then the old oxygen sensor came out easily. I did however use a really good oxygen sensor socket to break it loose (6 point Lisle oxygen sensor socket). Write to tell us if a new upstream O2 sensor fixed your vehicle too.
