so i have a 98 blazer 4x4 i cleaned the throttle body since it was caked in carbon. since then ive have a higher idle ( about 1k rpm ) then itll slowly drop down to about 600-700 and i have a P0507 code as well.

any idea? possibly the IAC?

 

Sticky IAC valve maybe, or failing. I'd start by removing it and cleaning out the passage that it's in and the valve itself, see if that helps your issue. Mine had this issue when the throttle plate restrictor came loose and one of the rivets came out, it allowed too much air through the throttle plate when cold. I wound up pullin that sucker off and blocking the holes.

 

yea i already pulled it off and cleaned the IAC, helped a little bit.

now i noticed a tiny hole in the center of the throttle plate that was originally blocked off from the carbon and i cleaned it out so its opened up. could that be part of it as well?

 

Yeah that could be part of it. There's a small hole in the center, then there's 2 rivets holding the restrictor on, the small hole is supposed to be there, if the rivets come loose and let air past that's when it's a not normal condition. which is part of what happened to mine when it threw that code.

 

clean your egr valve

it might be stuck open causing high idle

here is some information showing how to clean it

https://blazerforum.com/forum/articl...leaning-40424/

 

i took off my EGR roughly 5 months or so ago and quickly cleaned it, just moved the valve in and out but didn't actually "clean" it so ill pull it off this weekend and try that