Impala 3.8 2001 - Lower intake gasket ?'s.

I went in because I thought my CAT was clogged, due to a loss of power. I was not in the shop very long when they called me out and showed me the Lower intake is leaking oil/antifreeze. He did say even if the CAT is bad and I replace it, with this leaking could just cause the new CAT to go out, and he said plus this is a worst problem then the CAT being messed up.

With that said.

Is that an Honest reply?
They gave me a price of $700 to replace the lower intake Gasket. Does that sound like a fair price?
When that is changed what all gets replaced during this process? Just the Intake Gasket's (lower and upper)?
Is there anything I should have changed at this time? They also told me to change out the Plugs, even though I just did 5 months ago.All help is appreciated,
Lonnie

Also I'm not loosing any Fluids. I know if I go 6,000 miles between Oil changes I have to add a Qt. And I do have a small drip in the garage, which seems likely.

I asked if I had antifreeze in my oil, and he said I would have to have over 3,000 miles on that oil before I could tell. Which does not make much since to me, and if the two are not mixing why would that have anything to do with a new CAT going out.

They also said they could not test the CAT till I fixed the Lower Intake Leak?

If antifreeze/oil is leaking into the combusiton chamber, it could foul up your plugs, so maybe new ones are needed. Removing them and looking at them would tell you that.
$700 sounds about right, but I would definitely get a second shop to look at it also.
Anitfreeze in the oil should show up fairly soon, depending on the size of the leak. If it is a tiny leak, maybe it would take 3,000 miles, but if the leak is that small, I might choose to leave it alone until it becomes larger.
The lower and upper intake gaskets on the 3.8 are a somewhat common problem area, not as common as on the 3.4 though.

Well took the car to the deal, it was the CAT. I got lucky because I have 126500 miles on the car they still covered it under the 120,000 miles.

I asked about the leak in the lower in take. They told me to keep an eye on it, to make sure it does not get any worse. As of right now I'm not lossing much oil and I'm not losing any antifreeze. So I will try and get that fix Late spring.