I cannot seem to figure out what the problem is here. 2000 frontier 4cyl 5 speed. Whenever and wherever I'm driving the truck it just feels slow. If I step on the gas in third or any gear it just makes a bogging out sound and slowly gains rpm. And while accelerating I can feel the truck hesitating like I'm feathering the pedal. Which I'm not. Just seems like when I want to get after it the truck will rev out but just feels like the thing isn't going anywhere. Have changed fuel filter. Plugs. Wires. Air filter. I'm new and don't know what to do. Any help much appreciated.