Why is my 99 Olds Silhoulette overheating when you are in idle Dont know if its the fan motor cause the fan kicks on when the gauge is almost on the red?

Electric fan motor should kick in when your temp gauge reaches the halfway point on the gauge. Check with a certified mechanic, not a shadetree, to check on this. If you are driving it hot, YOU WILL REPLACE the engine sooner or later. The engine is quite fragile in your van. I know, had the experience, and cost over $5,000 to replace engine with warranty. You need to act now to save money in the long run. Have it checked out, spend some now, or a lot latter.