89 Dakota overheating

Its normal for your temp gauge to read higher after you shut down... your fan blade has stopped & coolant is no longer circulating .Any residual heat trapped in the block is being soaked out. You can try raising idle up a little for a minute ,then shut down and see if that helps. I was running a brand new John Deere excavator last week and I needed to stop for fuel. I idled for a 1-2 minutes to cool the turbo, then shut down. After I finished the fill-up,I restarted it and the temp warning light was flashing and the temp gauge was pegged. It only took 30 seconds for the temp to drop right back to mid range after hitting the key.