Here is the removal procedure, and the procedure is the same for both the V-6 and the V-8 Vortec engines. Also, be certain to put engine oil on the "o"-ring seal for the fuel injector assembly before installing the upper intake. Let me know if you require any further assistance.
1. Disconnect the battery negative cable assembly from the battery negative terminal.
2. Remove the air cleaner assembly.
3. Remove the wiring harness connectors and the brackets and move aside.
4. Remove the throttle cable and the bracket from the upper intake manifold.
5. Remove the cruise control cable, (if equipped).
6. Remove the fuel lines from the intake to the rear of the block.
7. Remove the ignition coil and the bracket.
8. Remove the upper intake manifold.
1. Install the upper intake manifold gasket.
2. Install the upper intake manifold. Use care not to pinch the injector lines between the upper and lower intake manifolds.
3. Install the upper intake manifold bolts. Note the marks made at disassembly for proper stud location. Install the two corner studs first in order to help align the two halves. NOTE: Other than the two torque passes listed below, the OE Manufacturer did NOT address or supply a bolt tightening sequence for the upper Intake Manifold for this model year, or other model years where this 2 piece manifold setup is used. A "Play It Safe" final tightening sequence would be to tighten from the center most bolts to the outer most bolts.
4. Tighten the bolts in two steps: a. Tighten the bolts on the first sequence to 5 Nm (44 inch lbs.). b. Tighten the bolts on the final sequence to 10 Nm (88 inch lbs.).
5. Install the purge solenoid and bracket.
6. Install the ignition coil and bracket.
7. Install the PCV hose et the upper intake manifold.
8. Install the fuel lines from the intake at the rear of the block.
9. Install the cruise control cable (if equipped).
10. Install the throttle cable and bracket from the upper intake manifold.
11. Install the wiring harness connectors and brackets.
12. Install the air cleaner assembly.
13. Connect the battery negative cable assembly to the battery negative terminal. - Tighten the bolt to 15 Nm (11 ft. lbs.).