Hi, got a 2000 Ranger 4x4 4.0 liter. Truck runs great but lately when going up a hill say 35 to 45 mph seems to start bucking a little. It's hard to tell if it's a shifting problem or something else. When I give it more gas like to down shift it seems to smooth out. Anybody have any idea's what causes this? Thanks Randy

 

i would try cleaning out the throttle body

 

How many miles on it? I am betting that you need to change your plugs and wires

 

Good luck figuring it out. I've had the exact same problem for a year. I get no CEL. Tried cleaning TB, new plugs and wires, new TPS, new IAC, new idler and tensioner pullies, changed back to paper air filter, cleaned MAF, new trans. fluid and filter, and tried unplugging the EGR. That's what I can think of off the top of my head.
Thinking of looking into cats, or computer. Maybe intake gasket.

 

He has an '00. different engine and probably transmission.

 

I had this same problem, Changing plugs and wires fixed the problem!

 

Thanks for the idea's