> When replacing the IAC is there any specific procedure to get it set
> to "home" position before reinstalling?

> Can you give a good description of the location of the test point for
> setting the Base idle? What does the connector look like? Color?
> Round? Square? Location?...?? I am not comfortable shorting out
> random connectors.

There is nothing to set on an Idle Air Control valve, just plug in the connector securely and mount in the rubber padded clamp on the intake manifold strut. A little dielectric grease on the contacts and around the rubber connector to seal it up against water wouldn't hurt.

As for test points and adjustments, I don't have an '88 diagram, but somewhere in the following idle thoughts should be the information you need.

LH 2.2: open rectangular plug with two wires, one Green/White (O2 measure point), one Red/White or Red/Black (IAC disable when grounded), located right side fender wall forward.

LH 2 on B28 engine: open plug with two wires, one Pink (O2 measure point), one White/Black (IAC disable when grounded), located left side fender wall forward.

LH 2.4 (or any 2-wire IAC): no test lead, just remove the electrical connector from the IAC valve or disconnect the IAC connector ground lead. For OBD equipped systems, test type 2, function 3 can be used to check the operation of the IAC. This test repeatedly fully opens and closes the IAC (plus injectors and other solenoids). It can sometimes even be used to free a slightly sticky IAC without having to remove it.

Alternatively, for any type of IAC, just remove both hoses from the IAC and plug the ends (try the ceramic end of a spark plug). An even simpler alternative is to clamp off one air hose going to the IAC being careful not to split the hose. Try small wood scraps sandwiched with a c-clamp or wrapping protective rags around the hose and using locking jaw pliers.

With the IAC close, the target base idle speed is about 700-750 rpm (fully warmed engine), or about 50 to 150 rpm below the nominal idle speed for the particular engine and transmission. The base idle is set with a fully warmed, well-tuned engine with the A/C off. If the engine tends to stall when the A/C is in use then moving the base idle up closer to the nominal idle may help (for LH 2.4 first verify that the A/C pressure signal is actually getting to the ECU).

The idle adjuster (black thumb screw) should allow the idle to be varied between about 500 and 1000 rpm. If you can't get this response and the idle is too low then the seat of the idle adjust screw may be plugged with grunge. If the idle is too high then you may have a vacuum leak, a dirty or stuck throttle plate or misadjusted throttle linkage.