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Join Date: Feb 2008
Location: United Kingdom
Re: 147 Not very well, Help!!!
OK, have you filled up at a different garage recently, this has been known to happen with "dirty fuel", cats just don't cause a drop in power unless they get blocked, I would therefore conclude that your description of the peower loss is more consistent with a faulty MAF.
There are visual things you can check too, oil/water down the plug holes will make it lumpy and is the temperature rising to 90 and staying there.
So for the price of them I'm wary of changing cats, rarely are they faulty, more often the post cat sensor is the fault.