Vervish

iTrader: (4)

NM - reread your post and the airbox has been checked.

I had a similar issue a long time ago and it turned out that the Lexus dealer who performed my oil change checked the air filter but did not correctly reseal the airbox after their inspection

larryp2023

Back with the limp mode
So basically, I just now installed new spark plugs. NGK spark plugs they were $30 a piece. I noticed a slight performance difference but the car still doesn’t have that kick back and acceleration isn’t as fast as it used to be. Also , the car kind of goes quite when you go wide open throttle. I would floor it, and then after the second intake opens up it doesn’t sound as loud as it used to be.
Any guesses ?

I got a new intake, I changed the spark plugs , I cleaned my maf, I cleaned the throttle body. I pulled out the two fuses to reset the Ecu. I also reset the ecu unplugging the battery. I cleaned the fuel system with the fuel cleaner. I’ve been filling up at shell only. My car only has cats after the headers. Not on the exhuast.

what else could I check?

lobuxracer

iTrader: (2)

NGK plugs? Why not the OEM Denso plugs?

isfvss

Cats arnt clogged up ??.

larryp2023

I was told to go with NGK , their a bit more expensive than OEM.

larryp2023

my exhaust doesn’t have cats, but I do have cats under the headers. Could those be clogged ?

lobuxracer

iTrader: (2)

I would not have recommended that. I am a big fan of start with the OEM parts and go from there one change at a time.

flowrider

iTrader: (9)

Who told you such a thing More expensive doesn't always mean better

This site is a treasure trove of information on the ISF and other models. Learn to use the search function.

Here are a couple of threads that might interest you:

https://www.clublexus.com/forums/is-...-2008-isf.html

https://www.clublexus.com/forums/is-...ark-plugs.html

There are more threads concerning spark plugs. They're yours for the searching.

larryp2023

Someone in that thread had the same issue I had where the car falls flat on it’s face at 5500 rpm’s when full throttle
I have the same spark plugs he re installed . The NGK iridium’s. Car feels better but it’s not back at 100% power.

anyone know what else I can check ?

JT2MA71

iTrader: (7)

Always use factory/OEM parts related to whatever you are trying to diagnose. Gotta narrow down the possibilities. I know you mentioned no codes but maybe run a scan of the ECU? If that's clean, check for exhaust system obstructions.

Idkyet2is

Well, did you ever find the issue?