Nissan Repair: Nissan Pathfinder 1989, nissan pathfinder, fuel filter

Question
I have an 89 Pathfinder, Standard. Now when im going down the road say in 4th gear, ill be going with my foot on the pedal not moving up and my truck hesitates to go. It didnt ever do it when I was going from 1st to 2nd ect, like starting out. Only when im going. So i think it could be either my fuel filter or some kinda of sensor. What do you think??
I have recently replaced all the spark plugs and that didnt help.

Answer
Hi Kristi -

I will need some verification -

Are you saying that when you are going up hills or accelerating the car hesitates or surges back and forth?

If so, what is the RPM when it does that, or is it various? And, only 4th gear?

Let me know -

thanks and aloha
calvin