gindyo

Some history first. I've had the car for 4 years now, it has 155k on it. And it has been having the issue since I got it, I found a temporary fix and have not looked for professional help, but it is getting annoying and I want to fix it once and for all. The problem is that it does not do it all the time (I may drive it for a week and not have any problems) and it is hard to find any consistent pattern of the conditions it happens under. It will most often (but not necessarily) happen when it is warm/hot outside, and I have driven it at a constant highway speed for 10-20+ miles. I mentioned that I found a temporary fix which is - I put the car in neutral and rev the engine up to the red for couple of seconds(may need to do that a couple of times) and the engine goes back to normal. Couple of year ago I looked on this forum again and found people who have some idling issues caused by the IACV and cleaning it solved their issue, so I did take the IACV apart and cleaned it, but it did not seam to help. I do not think it is the IACV because when it starts acting up you can feel the hesitation at higher then idle speeds, and you only really feel it when driving at a constant speed, it will accelerate fine when you step on it. Few weeks ago I changed the PCV valve and Air filter, but it is still doing it.

PFB

Remove the large snorkel hose ( don't remember if you have 1 or 2) located between the air filter housing and the engine, than carefully look for any cracks. You should bend that hose lightly to make any cracks evident

If you do find cracks,it means that unmetered air enters the engine past the MAF sensor. This could definitely cause the symptoms you describe and its quite common. If so, you can fix it temporarily with some electrical tape till you get a new hose.

ES300NZ

have you replaced the spark plugs ? and the leads (if any).

Mrv8q

There are 3 molded hoses there......

PFB

I think you are talking about the wrong hoses. The ones I was referring to are about 2" in Diameter, and look like a Snorkel, or an accordion. You can stretch them slightly. Can't miss them.

Don't remember ff there are 1 or 2 on that pariuar year es300

Phil

speedkar9

Check and clean your EGR valve and tube.