1998 Mazda 626 intake manifold removal/install help

Properly relieve the fuel system pressure. Disconnect the negative battery cable and drain the cooling system.
Disconnect the air intake hose from the throttle body. Remove the hose, resonator(s) and air cleaner assembly.
Disconnect the accelerator and, if equipped, the cruise control cable. Disconnect and plug the fuel lines.
Label and disconnect all necessary vacuum hoses and electrical connectors. Disconnect the coolant hoses.
Disconnect the EGR tube, if equipped.
If necessary, remove the air valve and remove the fuel rail attaching bolts. Remove the fuel rail and injectors as an assembly.
From below, remove the intake manifold support bracket.
If necessary, remove the bolt retaining the dipstick tube bracket to the intake manifold.
If necessary, unbolt the vacuum solenoid bracket from the manifold and position it aside. This will afford better access to the intake attaching nuts/bolts.
Remove the intake manifold-to-cylinder head bolts/nuts and remove the intake manifold assembly.
If necessary, remove the throttle body and separate the intake manifold upper and lower halves.

Be careful of this last procedure and how it is worded. There are some easier routes not mentioned either.

First, no, you do not have to drain the coolant out of the vehicle if you are just doing the intake manifold gasket. The only place the coolant comes in is where two small hoses connect to the IAC valve and throttle body. They can be plugged or just propped up to keep coolant from running out of them. Even if some coolant runs out, these two hose are at the high point of the coolant system so maybe an ounce or so tops will trifle out.

Secondly, the fuel system pressure goes away as soon as you remove or loosen the fuel line(s) going to the fuel rail.

Next, the "coolant hoses" mentioned are the two I mentioned above, not any others as lightning's procedure could lead people to do.

The air cleaner, rubber plenum, and resonator can be removed in one unit after lossening the hose clamp on the throttle body, removing three connectors (one bolt and two nuts) on the air cleaner housing, removing the large vacuum hose to the valve cover, unplugging the MAF sensor wire, and unplugging the inlet air temp sensor on the side of the air cleaner box.

The EGR valve is not attatxhed to the intake manifold.

The cruise control is not a separate connection you have to worry about, and if you are not 'benching' the throttle body you can even leave the throttle cable attached.

There are a total of town points where things connect to the intake manifold. There are some shortcuts here you can take. Some of the brackets holding various assemblies to the intake manifold need to be unbolted, and some you can leave bolted while only having to disconnect some hoses and wire connectors. Remember, you are replacing the intake manifold GASKET, not the intake manifold itself, so it is OK to leave some things attatched to it.