96 Lexus lx450 rpm change

[Shoelessjoe]

Hello all I recently bought a 96 lx450 with about 126,000 miles. The 80 series is new to me and have only had it for about 2 weeks now. I drove the truck home for the first time on the highway at about 75 mph for 2 hours an the rpm range was between 2200 and 2600 RPMs. I drove the truck again today and for some reason at 65 mph the truck was at 2900 to 3200 RPMs. I don't understand why this would change. The only thing that changed was that I played around with some of the features such as lockers, low range, and the gears on the transmission. Do I need to replace transmission fluids or what. Any ideas would be greatly appreciated. Thanks

 

[jfz80]

didnt by chance turn on the overdrive or power button did ya?
thats good for a 500 rpm bump
maybe its on and a dash bulb is out making it less obvious

 

[FloridaFJ80]

check the spring that provides tension to the brake pedal, mine had fallen off and I would have RPM spikes

 

[CJF]

You're either not getting 4th gear, or you are but the torque converter isn't locking once you're there. First thing to do is figure out which it is.