Picked up the GS300 mk1 just now, drove the 20 miles home and had a few issues.

First, I notice the idle speed has dropped to what appears below 500rpm causes a lumpy idle unless I gas it up 700 ish from when it's totally smooth.

Also, rather more worryingly, on right hand motorway bends at speed, the car seems to lurch from side to side almost like caught in a gust of wind.

Now when I picked it up the fuel tank was bone dry (as usual!) and I'm wondering if some **** has got into the fuel system from the bottom of the tank after I filled it up. Maybe causing crap idle and fuel starvation on the bends?

I've contacted the seller (trade sale) and he'll look at it but I'm wondering if anyone here has experienced similar?

As a reply to my own post I'll add this;

I just revved the bollocks off it, and took a trip to the local large open car park and threw it around tight right hand turns, can't replicate the problem. I'm hoping it was crap from the bottom of the tank in the injectors - keeping my fingers crossed!

hi, ive had similar . Bought an ls400 and drove it home and experienced intermitent juddering for abot a week. two £30 fill ups and nbow she runs fine. 3mths ago !!. I think it was dirt from bottom of tank. She was running on fumes when i picked her up lol

sounds similar

Cheers mate, although a reply from username 'Flogitt' scared me a bit!

Rough idle has come back now but I still feel it's crap in the tank, when i test drove it two days ago there was nothing like this. When I collected it, fuel gauge was right on the stopper and I;m the middle of Rochdale with a traffic jam in front of me so I risked a dive onto the M62 and headed for Birch and filled up there.

£75 quid! 1.04 a ltr. 72 ltr to fill up....

would be very surprised if it is crap in tank ,this was a problem years ago on old cars and not really something that would affect your lexus due to the amount of filters . could be old petrol that caused it and now you have filled up it could run fine

might be a dirty MAF sensor

Further to this, it's still happening, 99% of time everything is perfect but occasionally I feel the car lurching from side to side. Hard to describe but it's nearly always on the same piece of road, the worst being the slip road M60 to M61 at pendlebury if anyone knows it, 40mph RH bend but I've always taken it at full speed.

Now I'm not sure, cos I got my eyes firmly on the road, but I think the box might be hunting, but I really cant see how that could generate a lurching motion.

I'm still on semi-rough idle, but that's improving, and if I'm honest the lurching is only really 100% reproducible on that bend - could it still be the old petrol? I filled up on say - 75 quids worth, and stuck another 38 quids worth yesterday, gauge exactly on half.

Otherwise all is good

Are you sure its not just the road surface and the car handles differently than other cars you've had? Maybe check all your dampers are OK with a bounce test, just to see if one corner is on its way out?