2000 Nissan Altima

I bought this car new, have 73,400 miles on it, have always had it serviced regularly at a very honest dealership. Just moved and took it to a small repair shop for an oil change and to see why it was idling rough (and the service engine light was going on for a few minutes, then going off). They said it needs a new intake manifold gasket and quoted $540 to replace them. I called my old dealership--they said that sometimes the gaskets only need to be tightened, not replaced, so to have a dealer check it out. There is only 1 dealer in the area that doesn't seem to have a terrible reputation. If it is the intake manifold gasket, what is a reasonable repair cost? How is this diagnosed? Also, is a $95 diagnostic charge reasonable? You mention a handheld computer diagnostic tool that consumers can use--would that work on my vehicle too? Thank you.
December 11, 2006.

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