HowToRepairGuide.com: How to replace intake manifold gasket on 1999 Chevy Tahoe?

GO slow, BE careful.Technical and mechanical knowledge is required.Otherwise its hard job.But still,

Below are directions:

YOU CAN GO THROUGH:---
NOTE
Note the location of the manifold bolts and studs before removal for reassembly in their original positions.

NOTE
Do not disassemble the Central Sequential Fuel Injection (CSFI) unit.
Remove or disconnect the following:
Negative battery cable
Engine cover
Air cleaner intake duct
Coolant reservoir
Wiring harness connectors and brackets
Throttle linkage and bracket from the upper intake manifold
Cruise control cable, if equipped
Fuel lines and the bracket from the rear of the intake manifold
Positive Crankcase Ventilation (PCV) valve and hoses
Ignition coil and bracket
Purge solenoid and bracket

Intake manifold bolts and studs

Upper intake manifold

Clean the old gasket residue from both mating surfaces. Remove the following:
Distributor- make sure to matchmark the distibutor and the intake so that you reinstall correctly-do not crank over engine with it out
Upper radiator hose from the thermostat housing
Heater hose from the lower intake manifold
Coolant bypass hose
Exhaust Gas Recirculation (EGR) valve
Fuel pressure and return lines from the lower intake manifold
Wiring harnesses and brackets from the lower manifold
Left side valve cover
Transmission oil level indicator and tube, if equipped
EGR tube, clamp and bolt
Air conditioning compressor and bracket, but do not disconnect the lines

Loosen the compressor mounting bracket and slide it forward, but do not remove it.
Power brake vacuum tube
Lower intake manifold bolts and lower intake manifold

To install:

Clean all gasket surfaces completely.

Install the intake manifold gaskets with the port blocking plates facing the rear. Factory gaskets should have the words This Side Up visible.

Apply gasket sealer to the front and rear sealing surfaces of the engine block. Extend the sealer approximately ¹ / ₂ inch (13mm) onto the heads.

Install the lower intake manifold.

Apply sealer to the lower intake manifold bolts prior to installation.

On the 5.0L and 5.7L engines, install the bolts and torque in sequence as follows:
1. Step 1: 71 inch lbs. (8 Nm).
2. Step 2: 106 inch lbs. (12 Nm).
3. Step 3: 11 ft. lbs. (15 Nm).
Fig. Lower intake manifold bolt tightening sequence-5.0L and 5.7L engines

Install or connect the following:
WARNING
When installing the upper intake manifold be careful not to pinch the injector wires between the upper and lower intake manifolds.

Power brake vacuum tube
PCV valve and hose
EGR tube, clamp and bolt
Transmission oil level indicator and tube, if equipped
Left side valve cover
Wiring harnesses and brackets to the lower manifold
Fuel pressure and return lines to the lower intake manifold
EGR valve
Coolant bypass hose
Heater hose to the lower intake manifold
Upper radiator hose to the thermostat housing
Air conditioning compressor and bracket
Distributor
Upper intake manifold gasket
Upper intake manifold

Upper intake manifold mounting bolts/studs, torque in a crisscross pattern as follows:
1. Step 1: Torque the bolts/studs to 44 inch lbs. (5 Nm).
2. Step 2: Torque the bolts/studs to 83 inch lbs. (10 Nm).
  
  Purge solenoid and bracket
  Fuel lines and the bracket at the rear of the intake manifold
  Ignition coil and bracket
  Throttle linkage and bracket to the upper intake manifold
  Throttle linkage cable
  Cruise control cable, if equipped
  Wiring harness connectors and brackets
  Air cleaner intake duct
  Coolant recovery reservoir and the engine cover
  Negative battery cable

Start the vehicle and verify that there are no leaks.

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ALSO here are specifics for the distributor as this is the one were most people end up having issues with on intake gasket replacement:

Distributor:

Remove or disconnect the following:
Negative battery cable Spark plug wires and the coil leads from the distributor Electrical connector at the base of the distributor Distributor cap
Matchmark the rotor-to-housing and housing-to-engine block positions so that they can be matched during installation.
Distributor hold-down bolt Distributor from the engineInstall or connect the following:
Distributor, aligning the matchmarks are properly alignment Distributor hold-down bolt Distributor cap Electrical connector at the base of the distributor Spark plug wires and coil leads Negative battery cable

Installation
Timing Disturbed

Remove the No. 1 cylinder spark plug. Turn the engine using a socket wrench on the large bolt on the front of the crankshaft pulley. Place a finger near the No. 1 spark plug hole and turn the crankshaft until the piston reaches TDC. As the engine approaches TDC, you will feel air being expelled through the No. 1 cylinder spark plug hole. The timing mark on the crankshaft pulley should now be aligned with the 0 mark on the timing scale. If the position is not being met, turn the engine another full turn (360 degrees) Once the engines position is correct, install the spark plug.
NOTE Before installation, position the rotor so it points to the No. 2 terminal on the cap. As the distributor is lowered into the engine, the rotor will rotate clockwise and stop at the No. 1 terminal. This is the desired position.
Turn the rotor so that it will point to the No. 1 terminal of the distributor cap when it is fully seated in the engine.Install or connect the following:
NOTE If the distributor will not seat completely in the engine, remove the distributor and align the groove on the top of the oil pump drive shaft with a long screwdriver to match the tab on the bottom of the distributor shaft. Reinstall the distributor.

Distributor. It may be necessary to turn the rotor a little in either direction, in order to engage the gears.
Tap the starter a few times to ensure that the oil pump shaft is mated to the distributor shaft.Bring the engine to TDC again and check that the rotor is pointed toward the No. 1 terminal of the cap. If the marks are all aligned.Install or connect the following:

Hold-down bolt and tighten Cap and fasten the mounting screws Electrical connections and the spark plug wires

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For more car related problem troubleshooting:---

This are the sections, you can go through and click the link to read its troubleshooting.

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