hi i have a 1987 4runner with a 22re that is bone stock besides 30 inch tires. so here is my problem when driving on the freeway the check engine light comes on then if i let off on the gas for a second and get back on the gas the light goes away. i have looked on the forum for any info on this and couldnt find much. also i am thinking that im not getting as good of gas mileage as i should. i average around 17 mpg or around 260 miles per tank of gas.

 

Is that mileage adjusted for larger tires and factory gears? Doesnt seem too bad.

Sounds like an O2 sensor to me, but you need to check codes.

 

Ya the mileage is correct check with the mike markers on the freeway and they are just stock gears in it I assume they are 410s but don't know. I don't know how to check codes.
Oh I forgot to mention that I climbed under the truck a couple weeks ago and I noticed then o2 sensor wire wasn't connected so I re connected it

 

http://www.4crawler.com/4x4/CheapTri...CheckConnector

 

From my experience it is usually an O2 sensor, but I have seen a vacuum leak do the same thing as well.

 

when my truck did that it was throwing an egr code. get a paperclip and read the code. only way to be sure

 

In the 93 manual only three codes indicate they don't latch(stay on), VSS (42), STA(43), or Switch Signal(51). The last one (51) Doesn't get stored.

Now you have a 87 and I always have issues with that chart cause there are several of them It doesn't say which ones keep the light on or get stored, sorry. Happy paper clipping!