2001 Suburban high idle delayed shifting

My 2001 Suburban, 1500, 5.3L, 2WD with 164k miles, has a problem with high idle and delayed shifting. The high idle occurs when the vehicle has been driven around for awhile. When I start it up, even when already warm, idle is normal (~600 rpm). After some time, however, it idles at 900 to 1100 rpm. The delayed shifting happens right away--almost like I have the tow/haul mode turned on.
I have cleaned out the idle air port, cleaned the MAF sensor, replaced the idle air control valve, replaced the PCV valve, replaced the engine temperature sensor, and unhooked the battery to reset things. It still idles high.
I first noticed this a few weeks ago when the battery died. After I put in the new battery, the idle was very low. So I cleaned out the idle air port and valve. Then it was high. I drove it around for a few days like that and then started replacing stuff, to no avail--still high. Any suggestions?

P.S. I also cleaned around the throttle plate.

I rushed out to buy parts before reading the manual. The factory manual says to idle the warmed engine in drive for 5 minutes, then in park for 5 minutes to reset idle after disconnecting power. That seems to have worked, so I just wasted upwards of $200 in unneeded parts.

I rushed out to buy parts before reading the manual. The factory manual says to idle the warmed engine in drive for 5 minutes, then in park for 5 minutes to reset idle after disconnecting power. That seems to have worked, so I just wasted upwards of $200 in unneeded parts.

the battery replacing and the low idle is normal ... this is why there is the idle reset procedure ... then you say it idled too high after you cleaned up the TB/IAC.. using throttle body cleaner only NOT CARB CLEANER the IAC may have gotten stuck if you tried to rotate is pindle valve... or when you installed it the O ring did not seat correctly. when installing this needs some oil on it... high idle and a delayed upshift can be a vacuum leak as this will throw off the shifting since the PCM does monitor RPM and MAP / manifold vacuum............. cleaning these should be done @20-30K miles. MAF requires a MAF cleaner since electronic components are exposed to the cleaner solution. using the wrong cleaner will cost you..

After a week the truck is still idling and shifting fine. The reset seems to have worked.

After a week the truck is still idling and shifting fine. The reset seems to have worked.

the reset may have caused the IAC to move again.

if you tried to move the IAC valve then this is why it changed when you cleaned it.