Q: How to remove and install the intake manifold and its components in 2.8L,3.1L V6 engine on 1997 Pontiac Grand Prix?
A: To remove the components, first relieve the fuel system pressure, then disconnect the negative battery cable, ensuring the Theft lock audio system is off if applicable. Next, remove the EGR valve at the plenum, followed by the plenum, fuel rail, and injectors, being prepared to catch fuel and cap the fittings to prevent contamination. Remove the serpentine drivebelt and drain the cooling system, then take out the alternator and loosen the bracket. Unbolt the power steering pump if equipped and set it aside without disconnecting the hoses, then disconnect the coolant tubes and hoses as necessary. Label and disconnect any remaining fuel and vacuum lines and wires from the manifold, then remove the valve covers. After that, unbolt the manifold mounting bolts and nuts, separating the manifold from the engine without prying between the manifold and heads to avoid damaging the gasket sealing surfaces. If installing a new manifold, transfer all fittings and sensors. Loosen the rocker arm nuts/bolts, rotate the rocker arms out of the way, and remove the pushrods that go through the manifold gasket. For installation, ensure the mating surfaces of the cylinder heads, block, and manifold are perfectly clean, using gasket removal solvents as needed. Lift the old gasket off, use a gasket scraper to remove all traces of sealant and old gasket material, and clean the mating surfaces with lacquer thinner or acetone. Use a tap to chase the threads in the bolt holes if necessary, and use compressed air to remove debris, wearing safety glasses for protection. Apply a 3/16-inch bead of RTV sealant or equivalent to the front and rear ridges of the engine block between the heads, then install the intake manifold gasket. Install the pushrods and rocker arms, carefully lower the manifold into place, and install the mounting bolts/nuts finger tight, tightening the vertical bolts first followed by the angled bolts, ensuring to coat the bolt threads with pipe thread sealant. Tighten the mounting bolts to the specified torque, starting with the vertical bolts to keep the lower manifold centered on the gaskets. Finally, install the remaining components in reverse order of removal, change the oil and filter, refill the cooling system, start the engine, and check for leaks.