I've been having trouble with a rough running engine in my '97 4Runner (3.4L V6). The problem first started about a year ago when it suddenly began to run very rough on the highway and my check engine light came on. I took it to a mechanic who said there was a misfire code and changed the spark plugs and wires.

The problem seemed to be solved for 4 or 5 months until it gradually began running rough again and eventually the engine light showed up again. Not wanting to shell out another couple hundred bucks I changed my own spark plugs to see if there was just some fluke with a bad spark plug.

Well, again, the problem was solved for another 4 or 5 months. But again, it has started running rough and the engine light is on. Any ideas?

I don't have much experience working on engines, but I consider myself mechanically inclined and a quick learner. I would really rather try to fix it myself, because I don't have the money to have it done for me.

Thanks!

 

There is a link to factory service manuals in my sig that you may find useful, they have pretty good trouble shooting guides.
I had a 97 4runner that I got a misfire code on and it turned out to be the fuel injector.
At the auto parts store you can buy a tool that reads the check engine light for codes for about $30 the one you need is for obd2. You will also need a ohm meter for testing components such as fuel injector.

Hope this helps

 

Post/search the actual code to get a better idea of what is going on. Could be a few things like a bad coil pack.

 

Did any of the spark plug tubes have oil in them?