Bmoney

1989 4L auto was idling fine cold and FAST when hot

2000+ rpm in drive while coasting makes for some FUN offroad experiences!

What I did after a lot of noggin poking and reading up on causes here.

Of course refreshed the grounds at the dipstick (again, it'd been a couple years) and checked function of all vacuum related to idle.
All was well, still FAST

Removed throttle body and cleaned.
IAC was cleaned
TPS tcalibrated
New gasket for TB
STILL Idling WAYYY fast.

IAC verified to be working by looking in the port for it with the breather tube off.
Plugged the hole with my finger where you can look in and see the iac plunger and still revving way up.
That was where I got to thinking, where is all the air getting to this unit?

Heard some mention about tightening intake and exhaust manifold bolts.
That was the issue!
They're a bit of work to get at ALL of them above and below BUT voila! no more 30mph cruise on the trails.

Bmoney

Taking the torx bolts out of the TB for the intake was a rusty mess so I swapped them for some bolts that take a 10mm socket instead.