Yakuza

This is quite a story! :) I can help as I'm very local to you and GS300 owner and other similar for years. Please send me Private Msg me urgently. I really think you need some guidance before you blow that wodge of cash mate. Post back here if any probs with Priv Msg'ing (new?)

Spark plug gap?

Hey! I think this is bottom ball joints, and your problem too. My discs and pads are perfect (new) and I get the 70-60mph wobble thing... it's ball-joints and/or other links. This is typical. Discs just made mine *slightly* better, but no fix.

Watch for pipes with length-wise cracks too.. tricky to spot when cold if you don't bend the pipes right. Just remove all vac hoses (thin rubber hoses) and replace, looking for condition as John says. Sounds like air leak post-MAF. Does it ever misfire through the revs under throttle? coilpacks... or spark breakdown anyways.

The gearbox only switches into overdrive above a certain temperature (by sensor), and there are two speeds sensors, gearbox and one for speedo. That's why there is some confusion with japanese import speed conversions causing problems in the UK. You really need that gearbox error code. It's worth the time/money to get it.

Fuel ECU - well documented fault for stalls and engine cut-outs when warm especially. However, have you got a fault relay in your fuse box that is responsible for the complete cutout?

Recirc air helps keep it icey cool.. rather than fresh air mode. Get a digital thermometer on the air con output, and measure it. As temperature is often confused with humidity in aircon systems.

lovely motor mate. I like the wide rear alloys especially on those pics. More pics plz... :)

I've got the exact same problem, and I've already done brand new discs and pads. It's still there! argh! only over 70mph as you say, and under light to medium braking and then gone below 60mph totally. I've been advised by Lexus mechanic that it may be one of the arms (as it's multilink not double wishbone there's loads of arms) and/or ball joints. Best bet recommended to me was the arms first as they're cheaper, but it's still big bucks. Any thoughts guys? Would the wheel bolt torque make a difference *immediately* on brand new discs and pads?

new batt mate.. this does weird things when apparently not at fault, when actually it's not got the juice. These 2jz's either fire-up or they don't. I've seen the dashlight light up like a xmas tree flashing on a bad batt (trickle-charged, boosted, you name it). Just wait till the alarm goes bonkers on a dodge batt.

someone can confirm that the gs300 has sprung seats... hope so, just assumed. <sigh> just not convinced that the seats with much less mileage are more comfy or even the same as a Soarer yet.. and they were the bog standard seats - the old Lexus mantra "you arrive as refreshed as when you left".

I see all the same things that you're talking about with the "sometimes" slight hesistation to select gear... and slight slow pickup "sometimes". The rev raises, do you mean around 2k-3k rpm? As that's torque converter lockup and that's the super smoothness. The "sometimes" thing - I've tried one thing out. It's the i- in the gearbox, the intelligent part working out your style, and quickly too. If you are driving in super-slow traffic and then take-off, there's a slight delay while the ECU works out what's going on. And the same coming down the gears. Try this... cruise 20mph, and then give it a bit of power - feel the lag there, a bit too much. Now seconds later, cruise again at 20mph, and do the same.. It'll pick up this time. Whack her in sports mode, and try some spirited driving - the box soon works out that you're not messing around. It's all Lexus smoothed ECU algorithms to provide that smooth pickup over surging I reckoned. Sometimes makes the the VVTi-ed 3L engine feel more like a turbo in response, but the weird thing is the increase in torque as the revs go up to 5k-6k. Weird after the 400bhp 1JZ and the other (standard hp.torq) turbo'ed diesels that I drive. oh, and one last thing. Black gearbox oil is BAD news in an auto-Toyota/Lexus. There is a gearbox oil filter, but even the service recommendation is the life of the box. Basically, it shouldn't be black. Or just red?

I know what i'm talking about here. Have you considered replacing the Fuel ECU? This really sounds like Fuel ECU failure from many other experiences with your motor. Cost 200 quid or 2nd-hand maybe less than 100. To diagnose before spending cash, you need to bridge the fuel ECU out at the diagnostic port. Where are you at? where is the car and who's got it in for work?

For alignment - be sure they use 4-wheel alignment. Ask for print out. Even some dealers are not trained in the use of the kit - so the answer "yes we own a 4-wheel alignment setup" is not enough. I've driven 100 miles to the right place for alignment. It's that important, notwithstanding that the bushes will wear and change alignment from perfection anyway.