Weird Idle

[BadBowtie 98]

Hey everybody i got a 98 k1500. When i first start the truck it'll idle at 1000 rpm then it'll drop around 600 when i put in gear, but if i don't put it in and just let it idle it'll go to 600 also, but it will eventually go back to 1000 then drop to 600 again.

Anyone had this problem before, or have any ideas what the cause may be, is this normal? I was thinking some sensors bad, but have no idea which one

 

[GMstrong]

i had the same issue,i just cleaned and pulled out the iac valve alittle and replaced the tps sensor.

 

[BadBowtie 98]

i had the same issue,i just cleaned and pulled out the iac valve alittle and replaced the tps sensor.

Thanks ill try it!

 

[JonZ71]

Clean out the IAC

 

[BadBowtie 98]

Clean out the IAC

Where would this be located?

 

[GMstrong]

its located on the driver side right behind the thorttle position sensor.Its 2 small t5 screws iirc.