Goes to 3000rpm when clutch is disengaged

[QuebecRanger]

Hi, my Ranger is a 1990 XLT 2.9L with 4x4 option.
When I start it up it runs like it always has, but two to four miles down the road whenever I disengage the clutch my RPMs are higher then when I was in gear. It will never go over 3000 RPMs in neutral though. The RPM's will gradually descend while in netrual as my speed drops down. But if I am driving in third gear at 2500rpms and then pop it into neutral the rpms will jump to 3000.
Any ideas on what to do?
Thanks!

 

[KELLY88]

Sounds like the throttle has gotten sticky and when you disengage the clutch there is still some opening to the throttle body causing it to rev high without load. Either that or your idle air control is sending off some bad readings. How long has this been going on and have you done any upper intake work that may have gummed something up?

 

[QuebecRanger]

The only thing that has been done in the past year was a manifold replacement. But the problem surfaced a good couple of thousand miles after the fact. This has been going on for about two months now, but has been gradually getting worse and worse. I will try and grease the moving parts on the throttle. As for the Idle Air Control, my limited automotive knowledge leaves me a bit in the dust. Is this control adjustable or must be totally replaced if malfunctioning?

 

[KELLY88]

No it's not adjustable. It's just a sensor. However if it is going bad then it is cleanable. If the sensor is shot then that won't help but if it's just getting bad readings because it has gunk on it then cleaning it will help.

 

[QuebecRanger]

Thanks for the help, I am going to give a shot at finding and cleaning the sensor.

 

[KELLY88]

Alright good luck. It shouldn't be hard to find. It's right behind the throttle body on the upper intake.

 

[Zachalanche]

If it doesn't turn out to be a sticky throttle you may want to look for vacuum leaks. good luck.

 

[Stumpy]

My 2.9 was just doing that a few weeks ago, checked a couple things and it turned out to be the throttle position sensor (TPS). I would recommend checking that.

 

[RedneKRangeR]

the idle air control is not a sensor.
its an actuator.
could be either the three things mentioned thus far.

 

[nismotunedgtr]

You say the intake gasket was changed. Could be loose bolts making a vacuum leak.

Snug them all up

 

[QuebecRanger]

Thanks for the input everyone, I have some time this morning so if the rain lets up I'll give a few of these a shot.
Cheers!