the truck runs fine in park but when you put in drive or reverse it starts acting up, no power, back firing any ideas ya'll
i have changed the plugs, wires, throttle sensor, fuel pump, filter, checked the timming
Go to Advance or Auto Zone and get the Alternator and battery tested free. Odds the battery is going bad, but if the alt isn't putting out 14.5 volts it will cause it.