i just bought a 87 runner with 164K when I'm driving and i take it out of gear the engine will idle high around 2300 rpm but then if i tap on the gas it will idle back down to normal (around 650rpm) has this ever happened to anyone else? this is my first Toyota so i am not too familiar with these engines.
-thanks Dan

 

Several possibilities:

Sticking dashpot. The dashpot is that brass valve that helps return the throttle slowly for emission reasons. Usually it gets sticky overtime. I just spray the piston part of the valve with silicon spray.

Dirty throttle body. The throttle body gets dirty overtime from dirt that passes the air filter and crankcase vapors from the PCV valve and valve cover. The best way to clean it is to completely remove the throttle body and TPS (the TPS can be damages by the cleaner) and spray carb cleaner around the throttle shaft as well every orifice you can find.

Worn or damaged TPS sensor. The TPS (throttle position sensor) can get out of adjustment overtime. If the TPS is original and out of spec, usually it's best to replace it since the internal springs become weak and the TPS can never be properly adjusted.

TPS checking and adjusting procedure:


http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml