thanks for the knowledge. I, too, have the shimmy. I thought it was my tires so I had all new tires last week. Shimmy was a lot better but not completely gone. Thought it was my control arms. Glad to hear that’s normal.

 

yea it’s a pain but changing all the control arm bushings help. What really helped in my last gs surprisingly was getting new rims. I think a bent rim causes the shakes

 

I wasn't suggesting that cable had no purpose, it's just the kickdown cable, and not the throttle cable. And like a lot of things, if its not adjusted correctly, then it can cause issues. When you make adjustments to anything on the engine, you should reset the ECU, either with a scanner or disconnect the battery. So it can relearn the drivers behavior, and return the optimal performance for the current situation.
You always want to use OEM parts especially sensors, it's better to use an old OEM sensor than a new one that was manufactured in china. And unless the ECU is reporting there is a problem with something, then it's best to invest your money on the standard wear items. Brakes, tires, spark plugs, suspension bushings, etc, etc. There are plenty of areas that will need attention on a 25 yo car. So Any shimmy that occurs, can be identified and resolved. There are many suspension bushings that generate vibrations or unsual noises, and there are countless candidates that could be your culprit. Always try to identify the exact problem before you begin doing buying and installing new parts. Always try to confirm a part is bad before you replace it. This will keep costs down, and ensure your budget is used most effectively. The final subject brought up in previous posts, The 400 and 430 are rated with same power output. Anyone who owns a GS430, needs to get the ECU retuned for performance, you'll pickup a genuine 40hp without losing any driveability or reliability. Lexus increased displacement without increasing power output? Not sure why, but the did this by setting the ECU for low output. It can be easily accessed, you'll even more performance locked up in the '03-'05 GS430 that came with the 6speed trans. And again, it had the same rated performance as every GS400-GS430 made, but will perform much better with the appropriate tune. They usually set it up so you switch between higher power output or better efficiency,

 

That was what I did for my '06 430. Had all bushings, control arms, and struts(KYBs) replaced. Thinking of doing something similar to the '99 as soon as I sort out the car. I still have the belt service to think about. Seller(dealer) doesn't know if it had a belt service recently.

 

Checking back on this. After many many hours of reading and trying to figure out what was wrong, I went ahead and replaced the TPS but to no avail. I then replaced the throttle lever sensor 22060-50011 and took it to work this morning. It was a 25 minute job and so far so good. I can feel the immediate difference. No lunging forward at the stop light and no drop of the rpm when cruising. It was a small sample size (15 miles to work), but it certainly felt like I replaced the right part. I bought my TPS from Bell Lexus ($90) and the throttle lever sensor from eBay. The dealers were charging 2x what I paid for it, $200 shipped. Brand new OEM with the Toyota Denso engraved on the part. I was a bit nervous from buying it from eBay but decided to take a chance on it. I had bought a set of tire pressure sensors from eBay a few years back from a seller claiming they were OEM but arrived as after market.

I want to thank all of you for your input into this matter. Could not have done it without your help.

 

I’m happy to hear you got it all figured out. That throttle level sensor gave me similar issues on my 01 GS300 as soon as the engine warmed up. I thought it was something that only happened to the 2JZ-GE cars like the GS300.

 

Glad to hear you got that sorted out!

Hopefully I don’t run into that issue in my GS4.

Thank you for updating the thread because so many people never reply after they fix their issue and then there is nothing there when others want to search for the same problem.

 

I felt the same for many of the other threads I read. My next project for the car is figuring out who the previous owner is and if they've done the timing belt/water pump service. I bought the car from Cars and Bids from a small dealer locally so I have no idea who the previous owner is. I'd like to get the important things done first before attacking the handling department. I'll be posting the inquiry here on the forum later hoping someone knows the car.

 

it’s not on the carfax?

usually when the timing belt is done they write the mileage on the cover. If you don’t see the mileage they probably haven’t done it. Especially at that mileage you have it’s about right at the time it needs to be done which could be part of the reason they sold it. Usually if they actually did the timing belt they would mention it in the description.

you can also try and take a peak at the belt an experienced mechanic can sometimes tell if it was done or not

 

The serpentine belt looks pretty good. No cracks or anything like that. I was hoping I can push the belt service back a bit.

 

timing belt is different then the serpentine belt

 

Yes, I agree. You are right. I was thinking most people replace the serpentine belt the same time they do the timing belt and if the serpentine belt is an indicator of age and condition, the timing belt should be similar. I could be wrong in my thinking, too.

 

well if the serpentine belt is original and was never replaced you can probably bet the timing belt wasn’t replaced since that’s way more expensive and labor intensive.

 

The 98-00 GS300 and GS400 are notorious for faulty shift solenoids and crappy lbj’s. They corrected both issues with the 01 plus models.