1990 Lexus LS 400 "idle down" Questions

why does my 1990 lexus ls 400 idle up and down in park idle up and down in park idle air control valve is shot, replace it

High Idle High idle does not come down BAD IDLE SPEED CONTROL .the idle on this car's idle is controlled by the computer. Unless you have an accelerator cable is hanging up/stuck

...idle (goes up and down) and no trouble codes. sometimes it drives fine for 30 or40 minutes, sometimes it acts up after only 5 minutes of driving and never a chek engine light. HELP1 1993 Lexus LS400 ...

...down in idle I replaced the camshaft sensor and mass air flow sensor and code 13 is still coming up tachometer is rev up and down in idle and in drive at idle The RPM signal comes from the crank ...

down is the computer trying to slow the idle. Use a bottle of propane gas and a torch adapter with a rubber hose on it, spray the gas around the top of the top of the engine and alos around any vacuum

...down from idle to about 2500 - 3000 rpm's. And has not stopped doing this. I checked fault memory again, no fault stored. Any help will be accepted. Had same problem on 93 LS400, timing was off one ...

...idle on my lexus, the rpms are up and down and its missing while running? what would make the car start running like it is it was fine the night before then out of nowhere it starts to running bad. I ...

idle up and down on lexus 400 ls hard shifting 99% chance it is the computer. have it checked. ACE in davie Fl. can help. Auto Computer Exchange. They can test and fix your computer.

carwillnotidlecorrectly my cars idle keeps going up and down from 1000 rpms to 1800 rpms maybe a vacuum line has a hole or is off completely. it could be a brake booster even.

Acted like out of fuel but still idling. After playing with accererator awhile to keep running(it surged some while doing this)it finally started running properly You probably have a dirty fuel filter