Hanging idle

[Effieman]

So my 98 with the 4.0L was having issues where the idle would stay elevated for a few seconds before going to a normal idle. It would hang around 1500 for 2 or 3 seconds. I took off the inlet hose and shot a whole can of throttle body cleaner in it, making sure I got all the pivot points real good. Started it the next day and it worked fine....for about a day. Now it hangs at around 2000 rpm, and sometimes for longer than it did when it was only staying at 1500. All live data on my scan tool seems to be fine.
Any ideas/suggestions?

 

[alwaysFlOoReD]

Apparently this is a emissions thing on computer controlled engines. I noticed a similar hang while shifting my truck and it bugged the heell out of me. Yours may be the same.

 

[RangerReviver1990]

So my 98 with the 4.0L was having issues where the idle would stay elevated for a few seconds before going to a normal idle. It would hang around 1500 for 2 or 3 seconds. I took off the inlet hose and shot a whole can of throttle body cleaner in it, making sure I got all the pivot points real good. Started it the next day and it worked fine....for about a day. Now it hangs at around 2000 rpm, and sometimes for longer than it did when it was only staying at 1500. All live data on my scan tool seems to be fine.
Any ideas/suggestions?

The same thing occasionally happens to me. I remember one day i walked back into my house to let my engine warm up before i left my house and it just shot up to 1500 rpm and stayed there for like a minute or two. I thought my truck was gonna blow up. It stopped doing that but the only thing that happens now is if its hot outside, my truck’s rpm likes to fluctuate

 

[RonD]

Yes, on manual transmissions when driving the RPMs should hold high when shifting, for up to 7 seconds
Also hold at/above 1,000rpm with clutch pedal down when coasting or coming to a stop
When speedometer is under 5mph it should drop to normal 650-700rpm warm idle
It's all an "emissions thing"