So I'll post this up for tips and for the reference of any future member that may have the same issue. I was planning on selling the 4runner to get a tundra a month or so back, but got flamed on here for not posting enough info in my thread so I deleted it. Since then I've decided to keep the runner for now, but just ran into my first problem with the vehicle.

This week the truck began to run rough above 2000 rpm or so and would flash the check engine light if it was given a lot of throttle. Otherwise the light was off. Had it scanned at Autozone and it came up with a misfire cylinder #6 code.

Figured it was a bad plug, bad wire, bad injector or bad coilpack. Bought one ngk iridium plug since they didn't have any duals to sell me just to try to diagnose the problem. Also bought some injector cleaner and topped off the fuel tank hoping it might have been bad fuel.

On the ride home I got solid check engine light and vsc trac and vsc off light come on. Now I'm thinking the injector cleaner may have fried an 02 sensor or the cat!

Got home pulled the plugs on the drivers side and they all looked the same. I'm going to put this ngk plug in, clear the codes and see if there is any difference. If not I'll swap the coil packs and see if the code is thrown on a different cylinder and go from there.

I'm worried to death about a blown head gasket, but i shined a light down into all the cylinders and the pistons don't seem to be steam cleaned. I'll keep my fingers crossed on that one. Anyway, thanks to this board I'm able to save myself a lot of time diagnosing this issue. I'll continue to update and hopefully come to a resolution for future members to use.

I had the issue on my 3rd gen a while back, ended up being a bad injector

Put the new plug in, buttoned everything up and so far it's running good with no codes. If that solved the issue I'll feel like I've won the lottery. I'll give it 100 miles and if there's no issues I'm going to change all the plugs and wires and call it a repair.

Id like to hear opinions on the dual vs single electrode plugs. They gave me an ngk iridium single at autozone.

I had this problem for a while. Never triggered a CEL but every now and then it would studder under accelerating.

CEL finally came, reading said misfire. I replaced the plugs and its been running perfect for about 3500 miles.

Dual NGK or Denso, use no other IMHO. Such is for the design of the ignition system.

+1

I used Dual NGK