You may have to clean or replace you Idle Air Control (IAC) valve. Mine did the same thing, but after I cleaned it, I realized that it idled too low, so now I have to replace. Be forwarned... you will most likely have to order the part (it cost about $43.00) or you can get one from a junkyard if you trust that. Hope this helps.
The Throttle body is where all the sensors are for this car. If your having an Idle problem though, It is rarely that.
turn down your idle. theres a screw with a spring. right dab in the middle of the manifold with the injectors below the top part of intake. turn it to the left to turn it down. and so on
throttle body or idle air control value
water pump or thertomstat
If this happened all at once, check the vacuum lines. A cracked or broken line will cause high or rough idle.
If your 1991 Econoline won't idle or shift properly, it could be due to several issues. Common causes include a malfunctioning idle air control valve, vacuum leaks, or problems with the throttle position sensor. For shifting issues, check the transmission fluid level and condition, as well as the transmission filter. It's advisable to perform a diagnostic check to pinpoint the exact issue.
idle speed controll or tps throttle sensor
Go to the mechanic down the blocc
Perhaps the throttle plate is stuck - try to free with a screwdriver
A faulty camshaft can cause your 1991 Nissan Maxima to idle erratically. A diagnostic test could verify the cause of the improper idling speed.
Idle Air Control Motor malfunctioning.
The IAC (idle air control) at the throttle body is usually the problem.
With a tuner. Look into Diabosport or SCT.
The Throttle body is where all the sensors are for this car. If your having an Idle problem though, It is rarely that.
Check Related Link below. It shows you a picture too.
When you crank it? What are you driving a Model T Ford?
Could be your Idle air control valve.