I've got a 1990 Toyota pickup. The engine block and head are from 1994, but everything else is from the 1990. This is how I bought it, and it also came with a high idle.

When started cold, it idles very high for a few minutes. When it gets warm, it slows down to it's normal idle. I believe this means the IACV is working fine.

Even after it slows to it's "normal" idle, it is still higher than it should be. The truck doesn't have a tach, so I'm not sure of the exact RPM, but it is too high. I'd guess around 1200 -1500 RPM. If I spike the gas hard, it will then slow down to a nice, normal idle (probably around the desired 750 RPM).

My question: If once the truck is warm but still idling too fast, I spike the gas hard and that makes the idle slow to normal, what is the issue? Is something gummed up and in need of a cleaning? If so, what?

Thanks for your input. Looking for some direction before I go elbows deep

 

I have kind of the same problem. If I gently remove my foot from the gas pedal, it will stay at whatever RPM it was at. If I release it abruptly, it'll idle down just fine. It's kind of frustrating because if I let off the gas abruptly, my idle is great, but I have a horrible vibration from the rear end. Let off easy, no vibration, but jacked up idle.

I've noticed spraying the moving parts with WD 40 where the throttle cable attaches helps it for a month or so.

 

clean the throttle body and aic ports with maf (mass air flow) cleaner.

need to do this to my car and truck.

 

Sounds like a good idea. Humor me...what is aic? Thanks

 

aic= automatic idle control.
the holes on the bottom of the throttle body.

theres a thread where a guy sprayed maf cleaner into the aic holes, started the engine
(it dies immediately no maf signal) a few times and it cleared gunk out of the aic and fixed his idle problem.

 

Thanks man. I'll check it out!

 

I started the truck tonight to come home from a friends house, and I got to thinking about how it starts. It's not quite normal, then I remembered that the way it starts is how it sounds when the timing is too fast. When I got home, I turned the distributor back a little. It helped, and sounds more normal when starting now too. Maybe between this and the cleaning I need to do, it'll get straightened out.