why the high idle onmy 2001 olds siloheeteminivan?

I owned one of these but a '98. There is a little screw on top of where the top hose connects make sure that you unscrew it a little bit while engine is running until the coolant leaks out, you may have a big 'ol air bubble in there. that is what the screw thing is for. Also squeeze the upper hose with rad cap off and see if you can get any air out that way too. Changing the thermostat involves removing the upper intake, so you must have had to remove loads of stuff.

check also vac meter and see if you have a leak, remember the gas tank vent purge valve on the back of the engine and the rear crankcase vent hose (PCV valve), also the cruise control lines, throttle lines, etc. Its tight you could have a leak between the throttle and air mass sensor. good luck.

put it in drive and hold the brake. Check idle speed. If it is still high have the timing checked. If it is still idling high. Then adjust the idle at the carbeurator. Block thw wheels. Put it in drive then adjust the idle. And be careful!. Good luck.