Notice some slight hesitation when "hitting it" as I'm laying into it more to decide on drop, exhaust, etc. and testing car's true set-up. Read a post where spark plug change eliminates this. Is this common and did plugs stop it?

Only run 93+octane....

 

I suspect that the hesitation you are referring to probably has to do with the throttle-by-wire system and / or the automatic transmission. Unless you have something wrong with your car, spark plugs won't change it.

I have no idea what "more to decide on drop, exhaust, etc. and testing car's true set-up." has to do with this thread.

 

take off snow mode. if you haven't. exhaust wont make a huge difference in responsiveness. itll just feel slightly better.

 

To clarify, I'm testing the car right now (ie from standing stop, hard cornering, rolling start, etc.) to determine what I plan on doing in regards to future drop, exhaust... any changes really from how it is set-up today (how I bought it) vs future modifications and in the course of trying these scenarios out and "putting it through the paces" I started really noticing the hesitation....

Car is not in snow mode

Does that make sense?

 

I too am experiencing hesitation on accelleration. I've taken my 2007 to the dealer, which naturally found no problem after keeping it 2 days but only driving it 8 miles. I only use premium fuel from Cheveron - no cheap gas. The frequency of the problem is increasing. Also, my mileage has decreased by more than 10%. Grrrr...

 

Its natural and normal to have a hesitation when you have an electronic throttle system.

 

I'm fairly certain what I am experiencing in not normal. First of all, it is only intermittent. Sometimes, accelleration is smooth. Other times, I can take my foot off the brake, step on the gas and it's as if I'm not even touching the gas pedal at all. I can depress the accelerator at least half way down and I coast and then suddenly the power kicks in. People are honking at me because it's as if I am coasting through intersections.

I've had the vehicle for 11 months. This began happening about 2 months ago.

If this is normal, then this is my last Lexus.

 

This wouldn't be normal.

 

When the power kicks in does it suddenly slam you as you're pressing the gas? If so maybe your transmission is slipping. Stuff like this only happens on old or abused cars. Did you buy a demo car or a used IS?

 

Definitely not like a trans problem (been there, done that with other vehicles.) The car was new, with about 3 miles on it when I took delivery.

I will try to find a regional manager for Lexus service and see where that gets me.

It's pretty frustrating when my mother's 10-year-old, 4 cyl. Camry has more power sometimes.