Isuzu Repair: replacing IMG for the 3rd time..., intake manifold gasket, vacuum leak

Question
QUESTION: I'm getting ready to replace the intake manifold gasket(IMG) for the 3rd time now. twice in one year. I torq the bolts to spec, so i have no idea whats going on here. All I know is that when I take the Intake Manifold off, the gasket is in pieces. I am using all OEM products. Any suggestions would be appreciated.

ANSWER: Well Sean does the gasket start to leak? What are the methods you use to clean the surface? What year make and engine do you have?

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QUESTION: well, i guess it would of help to tell you the reason for replacing the gasket. First of all, its a 98 trooper. The idle is very erratic and the check engine light is on. Don't have the engine code at the top of my head. The whole vehicle has the symptoms of a vacuum leak but i am unable to find any leak. After further trouble shooting, I can only assume that it is the IMG. The first 2 times I changed out the gasket, when i took the manifold off, the gasket were in pieces. The method i used to replace the gasket was once i got the manifold off, i carefully picked all the gasket pieces out. then i took a shop vac and vacuumed up all the dust and dirt around the plenum. Then i wiped the area down with a rag to make sure there were no debris. Then replace the gasket and torq the manifold bolts all back to specs. it would be fine for like 6-8 months then the problem came back. i think thats about it. thanks again, sean

Answer
Well Sean I would consider a problem in your coolant. It could be eating away your gasket/s. Have you done a coolant flush and clean at all?? The gasket should be a high quality NAPA brand gasket as well as any sealant you might use. The high erratic idle would be an IMG leak and would cause a CEL to light. If you have any more questions though ever please do not hesitate to ask okay??