weird problem could be power sterring

[rangers92]

so i noticed a few days ago after a mild wheeling trip in my 2wd ranger when i took off form as stop and gave it gas the pedeal would vibrate(lightly) and make a small chatter noise for about 1 second then stop but only when i gave gas while the wheel was turned. i also herd and felt it happen a few times while the motor was shifting at about 2500rpm. i think it has to do with the pulleys or the power steering. the power steering fluid is brown lookign but not burnt black. truck has 104k on it its a 3.0(obvi). and help or insite would be greatly appreacated, its not a big problme i just want to know what it is.

 

[Rearanger]

fluid is brown

Should be ATF red. May have air in PS system. If you turn wheel while parked do you get vibrations up through steering wheel? Did you check level? I would flush and refill with new PS/ATF fluid.