I have a 2004 Ranger 3.0 V6. Almost every day on my way into work there is a slightly inclined road with a speed limit of 45. When I come to the road and begin to accellerate it starts bucking when it seems to be trying to shift to a different gear. Sometimes it makes a quick vibration like those white lines you run over when coming to an intersection.

Already replaced Plugs and wires.
Any suggestions??? Thanks!

 

how many miles on the fuel filter? plugged fuel filter will cause this.
if you are on a flat road and floor it, does it shift down smoothly and not buck or does it only do it going up hill?

 

When's the last time the transmission was serviced?

 

Just changed the fuel filter also.

Today i noticed it being worse on ice. Meaning more jerky. and I doubt it has ever been serviced. I got the truck around 60k miles and it just hit 80k.

It dont jerk as much on flat ground but yes is still does it time to time. I dont notice it being jerky if i floor it. only when I slowly accellerate in the 40-55 mph range. Its more as if it has to do with when its changing gears or trying to change gears.

It did throw a cylinder 1 missfire code and a new set of spark plugs seemed to fix that.

 

Well, since its probaly past due for a trans service I'd start there.
You're sure not going to hurt it by giving it a fresh filter and fluid.
I wish they put a drain plug on the pans. (Just rebuilt a 4r44e on my daughter's truck and didn't take the time to add a plug, D'oh!)
I change the pan contents every 10,000 miles on my SD and Yukon (had to add the drainplug to that one) which keeps fresh fluid in and doesn't 'shock' the system like a complete flush.