So I clean the IACV 3 weeks ago and everything when back to normal. Then a week later I decide to buy some mobile1 and pour it in... then idle goes low. It stays like at 300.
Did I use the wrong motor oil? It's a 94 LS non-vtec with b18b1 block. Btw, I just had oil changed like a month ago right before I throw the mobile1 in. Don't know if this a problem.

 

Did you bleed the coolant sys to get an air introduced by taking off the IACV ?. don't think the oil is the cause have you played with the idle screw ?

 

I agree with B_Swapped93. When you pull the 2 coolant lines off the IACV you introduce air into the cooling system. Bleed the cooling system and it will hopefully clear up the problem.

 

Not sure about bleeding. Do I have to do that? No I didn't mess with the screw.