You will need a 12 mm wrench.
1. Drain the engine cooling system (see "Replacing the coolant").
2. Remove the two bolts securing the support bracket (see "Replacing the cylinder head gasket").
3. Remove the throttle assembly (see "Removal and installation the throttle assembly").
4. Disconnect the wiring harness connectors from the injectors, the absolute pressure sensor in the intake manifold and the air temperature sensor in the intake manifold (see "Removal and installation the fuel rail").
5. Remove the fuel rail (see "Removal and installation the fuel rail").
6. Disconnect the hose from the intake manifold geometry change valve fitting (see "Checking and replacing the pneumatic chamber of the intake manifold flap drive").
7. Unscrew the two nuts of the mounting studs and disconnect the tube from the exhaust gas recirculation valve (for clarity, the valve has been removed).
8. Unscrew the two bolts securing the recirculation valve tube to the intake manifold, move the tube to the side...
9. ...and replace the tube gasket.
10. Loosen the power steering pipe bracket mounting nut...
11. ...move the bracket to the side..
12. ...and unscrew the stud of the upper generator mount.
13. Unscrew the generator bracket mounting nut (shown by arrow), two stud nuts and seven bolts securing the intake pipe to the cylinder head in the order shown in Fig. 5.6 (for clarity, this operation is shown on a removed cylinder head). Remove the upper generator mount bracket and intake pipe from the vehicle.
14. Remove the throttle body and intake manifold flange gaskets and replace them with new ones.
15. Tighten the bolts and nuts securing the intake manifold to the cylinder head in the order shown in Fig. 5.7 to a torque of 25 Nm.
16. Install all removed parts in reverse order.
(The source of the article is available on the website ChevyMan)