A friend bought an 86 4 runner that had kind of a lumpy idle. It also stutters enough to notice at around 2,500 RPMS.

Had hard starting issues and a "knock" sensor code.

I suggested replacing the TPS, which he did, which seemed to solve the idle issues, but it still ran rough at idle.

I suggested we clean and check the IAC solenoid, but it turns out this truck has an auxiliary air valve instead.

We take his apart and sure enough it's broken inside. We go to a bone yard and pick up another one, make sure the coolant ports aren't clogged.

We also checked his valve timing- it was good.

Turns out he just turned the TPS "All the way" one way instead of adjusting it, so I adjust it according to a post by "Frankencrawler" on another forum.

The previous owner had the idle stop screw screwed in so far that it completely bypassed the auxiliary air valve. I reset it, so that it's touching the throttle stop, plus a little more. 1/4 turn.

We had to reset the distributor but eventually got the timing right, more or less.

It starts now, but it refuses to idle. With the new auxiliary air valve, we are very confused as to why. Any help is appreciated!