This is all on my 98 .
Change your rad cap to a new one and flush your power steering.
Simple enough , so here is the reasoning.
By getting a new rad cap it will lower the temps by increasing the pressure. How does this help , it will cause the clutch on the fan from engaging as much. This reduces the load on the engine as well as gas consumption.
How to test yours?
Run the car for a few hours so it is nice and hot ,once it has cooled remove the rad cap from the over flow tank and listen for the release of pressure. if you do not hear it the seal on the cap is dead and needs to be replace for $20. time 10 seconds
If your have not changed your PS fluid lately and it is dark ,you should change it as it is causing excess load on the engine. I flushed mine with 2 liters of Mobil 1 synthetic tranny fluid. As soon as i was done it got really quiet and my fuel consumption has gotten much better. I went from 12.4L/100km to 8.8L/100km . Old dirty fluid is harder to push through the pump as well as the lines and rack will be dirty as well causing restrictions. The new tranny fluid has great properties of cleaning and has since cleaned my dip stick and interior of the PS res to a shine. Once the restrictions are gone it makes the pump push less and reduces the load again ,it also makes it very quiet.
Total cost $20
Time 30 minutes
tools/material, pliers to loosen clamps ,a black sharpie to block the return line on the side of the reservoir ,a hose to fit to the lower line (smaller of the 2 hoses from the res is the return)to a old washer fluid jug .
It works best with 2 people one to start the car and one to pour to keep it full. Do it once and then do it again in 2 weeks once the new fluid has cleaned up the rack and lines.
Make sense , now get out there and save some money and bring back that LS feeling all over again. My car is so damn quiet again, it is really unbelievable.