1996 c1500 issues

[TS6235]

These issues started after I replaced the ignition switch harness. High idle on start up, 1800 rpm or so then goes down to normal after 20 seconds or so. While driving on freeway, when I lift off the accelerator the rpm raises a couple hundred rpm's and seems to hang at the slightly raised idle until the truck is fully stopped. After warmed up, turn the truck off and restart it, it will start with raised idle for 20 seconds or so then down to normal, put the truck in gear and the idle raises without touching the accelerator pedal enough to keep the truck going 5 mph or more until you come to a complete stop again then the truck idles down again. No codes are being set. It runs and idles good except this this issue. I did unhook the ground from the battery a couple of times. Ideas?