Rev hang?

2006 tacoma -- 2.7L 5spd

This only pertains to a manual transmission i think. But anyone ever experienced their rig not idling down from the 3,000 rpm range in a timely manner, and notice that it kinda lingers in the higher rpm's even after you've removed your foot off the gas?

I replaced the water coolant bypass pipe awhile back and had to remove the umm.. air intake manifold from the truck, but i put it back on. There was a bolt or maybe two that were tough to get to, but also, i couldn't see the seal very well when it finally seated so im wondering if i could have a leak there? not sure. Any input or methods of checking this? perhaps shooting starter fluid in the general area with the vehicle running eh? To see if it idles the vehicle up?

Obviously don't want to shoot anything that's super hot and cause an explosion lol but idk. Any other ideas? Ive had the throttle body off and it looked ok, not real dirty, but im not sure if the little doodad flap inside of it was fully closed off at the return position.

any input is welcome

 

I noticed this briefly the other day on my 2012 v6. I typically try to sit around 2000 rpm on the highway, got on, accelerated up to speed, then let off the gas a bit and it just hung at 3000 RPM for 5-10 seconds before finally shifting. I haven't had the same problem again so not sure what the cause was.

 

For the v6's it's programmed in the ecu for emissions purposes. Can be deleted with hptuners (my truck has it deleted) but they don't support the 2.7 yet.

 

As stated above some rev-hang is normal but if you have a vacuum leak it would likely make it hang a little longer although any substantial leak would likely cause P0171/174 code(s).
If you had the battery disconnected it will take the PCM awhile to relearn it's idle strategy and rev-hang can be exaggerated for a few drive cycles.