Lexus LS400

In fact we ran into a real problem child, and it turned out to be bad gas. The only solution was to completely remove the bad gas. There is no magic additive. You must remove all the suspect gas. All of it. I suggest you just run the car until you are about to have to walk, then gas it up with gas from a station other than were you got the bad stuff. BTW, when we completely drained the tank, the injector rail, added new gas the hesitation, missfires, and backfires went away. This was on a different model, but your symptoms are exactly the same! Hope this helps! Oh, sorry I am a Tech working at a lexus dealer!

Hi saphfire Tech

My husband ran the car until it was almost out of gas and that is when he added the high octane with the seafoam ran it again until it was almost out and put more high octane in with seafoam. He cleaned the intake valves and cleaned the injectors. Changed the spark plugs it is running better, but when you get over 60 it begins to hestiate a little. He did not change the spark plug wires. A mechanic checked the CATS and said that they looked to be very hot. Could the CATS be stopped up or could it have burned up the spark plugs wires. Do you think that I need to change the oil and the wires or change out the CATs.

That is funny you brought up the CAT issue. I am assuming you mean the catalytic converters.
They were plugged on our problem child, but that made the car not start. These are very expensive. I am now
going to suggest you find a Lexus dealer in your area that has Elite status. That is very important. If you cannot find an Elite Dealer, You are going to need a dealer tech that understands a thing called Fuel Trim.
This will lead to a fix. I am sorry I cannot be more helpful
at this point. I recommend a dealer tech because they will understand the fuel trim numbers better than a non dealer tech. One thing, if you got water with that bad gas, unless the fuel tank is completely drained, and cleaned, that water will stay in the bottom of the tank.
Water is heavier that gasoline and will stay at the very bottom of the tank.
The fuel trim values are the key here.
Good Luck!
Cheers