Well to start off about three weeks ago a single ignition coil went out, so I replaced all 4 of them. I already have fairly new plugs and upgraded wires. So that fixed that problem. Then the following week my fuel Pump dies on me. Got a new one and replaced it. Everything seemed to be normal again, acceleration and fuel economy was better than ever.

Then this past week, it seems after I start driving during mid day when it's hot and humid outside I get a really slow acceleration in 2nd and 3rd gear. Its usually not right away though. After I've been driving for a mile or two it starts. Also, I noticed a different intake acceleration sound. I have the second generation K&N short ram intake. The sound gets really deep and scratchy when trying to accelerate. Sort of like when an ignition coils goes bad, but not as severe. And today it stalled on me as I pulled into a gas station. Which has never happened. Anyway, from what I've read it could possibly be:

1) My cat is going bad and should be replaced.
2) MAF sensor is going bad and should be replaced.
3) My Vaccum/ Compression in one of the rotors is bad and engine needs to be replaced.

Is there anything else I should check or which of these should I troubleshoot with first?

 

90% CAT is going bad.

 

I'm leaning towards the cat too. It is stock and has 76,000 miles on it. Would a bad cat throw the CEL on? Mine hasn't at all. Only when my coil went out.

Recommend a great high performance Cat?

 

well, u have another 4K miles to "kill" your cat so you can get a replacement for free under the federal emission warranty.

its easy ... but

aftermarket CAT? well, there are a few, rotary exhaust fume is too hot for most "regular" cats so ... have u search ?

 

Really? At 80,000 miles I can get a new cat from the dealer? That applys in TX?

Well from what Ive searched on here... the Exoticspeed Cat or the Racing Beat Cat.. but as far as Cats go, I don't really know whats worth the price. I mainly want a long lasting well made cat.

 

Federal Warranty is 80,000 Miles or 96 Months(8 years), whichever comes first.

So yeah, if your CAT "dies" now, or within the next 4K miles, yep, you will get a brand new one.

I do not think Racing beat makes any CAT for our cars. They make straight pipes.

not sure about Exoticspeed.

was it rx7.com ? I think they sell high flow CAT for our car.

but the longest lasting CAT is ALWAYS stock cat.

 

Well I'll definately look into that before buying a new one.
RX7.com actually had a descent price for theirs and gaskets. I wonder how much a stock one costs. I searched for it and it didn't come up on any good OEM parts sites.
Thanks for sharing your knowledge man. Definitely worth a try.

 

OEM cat cost 1500+ bucks.

 

go get the cat warranty , then buy another high flow cat for daily use, factory cat for smog.

 

Today as I was getting off the highway, as soon as I pushed in then clutch my RPM's dropped to 500 then seconds after it stalled. It started back up right away and RPM's returned to normal but the check Engine Light still didn't come on.

Does a bad CAT really affect it enough to make the engine die?
I'm just wondering if I have another problem.

 

You were sooo F'ing right man! Just got the call from mazda. They said my CAT failed and will be replaced for free under the emissions law. Didn't expect to hear that good news.

 

Good idea. Think I'm gonna do it.