I've been trying to figure out my idle problem for a few weeks, since I bought my 87 iroc. It has a 350 tpi motor btw. I tried swapping the MAF, IAC, but I am getting a weird idle. Startup is normally pretty solid. I notice a crazy high idle when shifting into park after a drive. Car will die when shifting into gear without me giving it some gas. In gear the car has a rough idle at a stop, ranging from 550-750 rpm. I can shift from drive to reverse and the car will sputter a little, but won't stall. Ideas?

 

I'd start checking for vacuum leaks.

 

Yea I've come to think you are right. I took her out and heard some hissing on the left side while driving. Sounded pretty close to the dash. I have no idea, the prior owner disconnected and plugged all kinds of stuff.

Now with a vacuum leak I really don't know where to look or the best way to check. Could I be directed towards pictures or vacuum leaks for dummies?

 

First thing to check would be a vacuum hose diagram for your car. If all the hoses/caps are there on the engine, then check the other end of the hoses for problems. Pull out the PCV valve and shake it. If it rattles, put it back - its fine. If it doesn't, replace it. Check the grommet and one-way valve (on the hose) to your brake booster. You should be able to blow through it in one direction, but not in the opposite direction.

Might also be a good idea to check the throttle position sensor's adjustment. Theres a process for doing that, but I don't know what it is off-hand.

 

A good start would be the Vacuum line and fittings.. if not that.. check your IAC and TPS for correct voltage and adjustments.