I have a new one for you to help with

I'm not a certified mechanic, but some things that could help you out here....
1)Drain all coolant from the system, fill with fresh water and a commercial cleaning fluid designed for coolant systems. Run the engine at idle until normal operating temp has been reached and let it idle for the recomended time on the bottle, then shut it off and let it cool.
2) Being an S10 the lines for the heater core are easy to get to, so get a flush kit that you splice into the heater lines. It will allow you to flush clean water through the engine block, heater core and radiator to clean all the nasty gunk out. Follow all directions on the package to install it, and run clean water through it until all water runs clear.
3) After flushing system, cap off the flush kit, and drain the radiator. Fill with a very high quality antifreeze/coolant mixed with water at the recomended ratio (or a little stronger if you did not attempt to drain the block).
4) bleed the system be running until it's fairly warm and shutting it down, keeping the radiator filled the whole time. Cap the radiator and let it cool. Add more coolant, and keep repeating until the level no longer falls in the radiator and fill the overflow bottle to the cool fill mark.

If the temp continues to rise too high, you can add an additive to the coolant mixture that makes heat transfer more effient.

Also change your oil, and use a high quality oil and filter.

If none of this works to help with your problem, then someone with more experience in cooling systems will need to help you out.

Remember to dispose of all old coolant, flush water, oil and any unused new coolant in an enviromentally safe manor.

If the water is brown I would agree on a cooling system flush. I would use a Prestone flush kit available everywhere and put a Tee in the heater hose line as instructed. They will do a good job. I would also look at the fan clutch. If it wont engage you will see the temp go up at idle every time.
lama