Bought a 95 4 Runner 4x2 v6 3.0 about two weeks ago and noticed it jumps up and down in idle. I have only changed the plugs after finding out the passenger side had different brand compared to drivers side and different gaps. Put all new NGK with .032 gap and noticed a little better response when accelerating.

I noticed the car will sometimes idle at about 900 rpm and will jump up to 1200 and sometimes back down again. It will not do this consistently up and down like hunting or searching or whatever you cal it. It will sometimes stay at 900 and maybe after a few minutes it will jump up and maybe 30 seconds down again then 10 seconds up again then down in 15 seconds. Have even shut the car off and started it right back up and it is up to about 1600 rpm and stayed until I started driving it.

Earlier today was at Home Depot and came back out and started but wanted to die, gave it gas and it rumbled low again and caught itself and was fine. This was the first time I ever experienced that in the two weeks I have had it.

I do not believe I have any vac leaks but did notice after I just sea foamed it that the passenger side gasket at the manifold to crossover tube was leaking. Sea foam "smoke" was blowing out of that 2 bolt connection pretty good.

Not long ago the guy before me replaced the head gaskets because it over heated and blew coolant through exhaust. All that seems to be fixed and it actually drives well! Just cant figure out the high 1200 rpm idle and the jumping up and down in idle. Driving and acceleration seems fine! Any Ideas?

 

check your coolant level. i know on hondas, when the coolant is low or has air pockets, it will cause the idle to jump up and down

 

I just topped it this morning. I am having one of those leaks on that back bypass coolant tube that I have noticed many others having the same thing. How do you get air pockets out of the coolant system? I am starting to go towards the coolant temp sensor which is back there as well! Most of my troubles comes to that sensor in the manual.

 

many ways to get air pockets out. the way i do it is: take cap off. start truck up and wait till its warmed up as i keep topping off the coolant if it goes low. onces its all warmed up and topped off. i cap it and turn the truck off. make sure the reservoir is at full or more. let it cool down. check coolant level and you should be set

 

Awesome thanks! Will try that in morning!