Ok, let me introduce my self. I am new to the board and my current truck is a 2001 2.7 4x4. Just picked her up about two weeks ago for a good deal.
She has 164000 miles and runs strong, no leaks either.
When I bought the truck it had a check engine light (P0410, catalytic) if I remember correctly. And the idle would creep up, a quick rev would bring it back down.
I narrowed it down to the IAC valve for the idle and thought I would replace both o2 sensors for the CEL.
Replaced both o2 sensors with denso factory units and the CEL went off but now I have this idle surge along with the creeping up idle.
Today I replaced the IAC valve, cleaned the throttle body and installed new gaskets along with a new TPS since the TB was on the bench. I also checked the MAF sensor and cleaned it also disconnected battery and drove for about 20 miles for the computer to re learn.
No creeping idle( IAC fixed that) no CEL but the idle surges bad. 500-1100 rpm every 2 seconds. Checked all vacuum lines and verified no leaks.
I am officially LOST on what to check. I keep thinking put the old o2 sensors back in and see if it still does it? Any ideas?