1996 Sidekick revs on its own when holding the gas pedal at about 2000 rpm

[sunrise7]

1.6 Liter, 5spd, 4wd, 93,000 miles on odometer

Weird symptom.  It's hard starting when cold, but once running and warmed up, if you hold the gas pedal at about 2000 rpm the engine will start
 to rev up and down between approximately 2500 and 1500 rpm.  If you depress the pedal some more it will stop the cycling and hold at higher rpms.
Its only at about 2000 rpm where this cycling happens.
Car runs fine on the road, even at speeds to 65mph....
Does smell like it runs rich, but it runs....

Any ideas as to what it may be? 
Something clogged in Throttle body?
Throttle position sensor issue ?
Idle air control valve malfunction ? 

Thanks......

[jwunsch]

I have 1991 8 valve 5spd and mine does same, but rpm being 2300 - 2500. In addition to that hot idle is not maintained correctly. My hot idle is about 800 rpm, but when I turn on high beams, blower full, seat warmer etc it drops to 600 rpm, so ecu is not correcting it.

Mine is most probably fucked by some carburetor guy doing his magic to fuel injection without understanding how the fuel injection works.

Fixkick gave me some info about it in following post: https://fixkick.com/forum/thread-vitara-...5#pid13045

Those actions will not work 1:1 with your newer car, but maybe it gives some points to try to check. And mine does it sill after fixing all vacuum leaks. Look especially where he says:

> this is the TPS idle switch set wrong. the ISC must go off line with right foot pressed, on your car it is set wrong, and the ISC is wrongly active fighting the right foot actions.

[fixkick]

1.6 Liter, 5spd, 4wd, 93,000 miles on odometer

Weird symptom.  It's hard starting when cold, but once running and warmed up, if you hold the gas pedal at about 2000 rpm the engine will start
 to rev up and down between approximately 2500 and 1500 rpm.  If you depress the pedal some more it will stop the cycling and hold at higher rpms.
Its only at about 2000 rpm where this cycling happens.
Car runs fine on the road, even at speeds to 65mph....
Does smell like it runs rich, but it runs....

Any ideas as to what it may be? 
Something clogged in Throttle body?
Throttle position sensor issue ?
Idle air control valve malfunction ? 

Thanks......

wow you nailed the top 3
the the iSC is stuck closed, but that surge hints he ISC is hunting like mad (we know it can)
the next poster nails the carb  guy screwed the TB stop screw the never ever touch screw, my TB page, i cure that set the screw so
tv plate has gap of 0.0005 " not a typo, and is closed 99.99% the gap is to  prevent TV from jamming to the bore only
the surge can be MAF errors. ever scan the PCM for DTC errors, from TPS or any thing that causes limphome.
the TPS in this car must be calibrated. if not   the idle switch is dead making isc dead.
the TPS late to open the idle switch causes the ISC to fight  the drivers right foot as he tips in the throttle with toe.


TV valve full of gunk cause air leak (illegal and causes TPS to lie)

first are scans why skip such a prime first step
gee tps errors/


see screwed again here

http://fixkick.com/IDLE-AIR/screwed-again.html


that hot idle 2000 rpm or more hints of ISC hunting and can be a huge air leak to the intake
the only legit air is from this path (not the TV) called metered air
1:maf  is the only 1 path that feeds these 3 below.
2: bleed screw  in the TB not screwed all out. or omg missing.?
3: the iSC path(electric)
4: the IAC path (wax thermal device)
that is all, there are no other pathes
one common failure now is the IAC thermal valve is dead. and stuck open and overloads the ISC for too much air.
the IAC must close 100% at 150f if not bad news, it is bad.

if that happens the ISC hunts but when closed air flows crazy high that the ISC can NOT STOP!
one way to prove that is block the IAC air port. covered on my 16v TB page

the air horn of the TB has a port there (IAC suck side) and I put clay there to block it for  a test. quick
do not run car with air horn open, to  TB .
the maf is not optional

the IAC port block test or the hard to remove screws on IAC below can be pulled and gasket blocked  the whole iAC.
the wax pellet in the IAC dies and shrinks and makes IAC dead, or leaks air.
see the no touch screw here.