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Hi. I've done some online reasearch and this problem seems to be common and often difficult to diagnose and fix. I have a 98 Toyota Altezza with the 3SGE engine which has difficulty idling when hot (irrespective of whether the aircon is on or off). It surges (or hunts) from very low, juddering idle up to about 1100rpm. It is a manual gearbox. There are no fault codes in the computer and no warning lights on. It has a new set of spark plugs and I have checked the PCV system. Can you please give me a checklist of items (starting with the most likely first) to run through to isolate the problem. I hope this is not too much of an ask. My feeling is that it must be a sensor fault but there are so many in play. I have also read horror stories of even Toyota not being able to solve the problem.... Thanks in advance. Glen

Hi Glen,
I've not heard much of this specific issue on the Altezza, however in general there are a few things to check. The most likely can be the throttle body and idle control solenoid, it might need a clean and the idle control system cleaned and checked. Failing that, cooling system issues can also play havoc with Toyota hunting idle- if you have had any recent work done on the cooling system there could be an air lock in the idle circuit. So two potentials that I recommend checking. The other thing could be to check that there are no air/vacuum leaks around the inlet manifold gasket, pipes, and hoses on the manifold.