Weird problem help please

[TwIsTa]

I did a search found some things that sound like my problem, possibly the cat.
Well im pretty sure my cat is out since when i start my car when its cold thiers this nasty rattleing coming from under my car but i havent taken it to get fixed. well lately and the worst happend today when i drove out to Las Vegas. When i floor it my car screams like its flying but thier is no power then all of a sudden bang it takes off like a bat out of hell so im like whatever. well im driving and every time i floor it the same thing just keeps happeing the whole time and my car is not picking up speed at all so i jump into the truck lane. i look at my thermostat and my car is near the red line im like great and my service engine light comes on. Then my thermostat goes down like its suppost to so i just keep on driving to vegas my car finally starts acting right. so im on my way home i try to pass this slow car and my car stops at 65 screaming at about 3-4000 rpms and im actually loosing speed. so i have to drive in the truck lane and my car does this about half the way home. then all of a sudden i hit a hill and my car is driving fine and it stayed fine. and now its acting like nothings wrong and the service light went out and everything. is this just my cat? Im sorry if i just babbled i havent slept in 32 hrs. any help would be great. thanks.

[digitalballz]

Get the car scanned to see what the SES light was, and start from there.

[TwIsTa]

Ok so i took it to autozone got it scanned came back as a P0306 6 cyl misfire. so i asked the guy what it could be he said more than likely just a spark plug or the spark plug wires, yes the spark plugs on my car are very old so im like cool i have a coupon ill go run down to econolube for 35 bucks and get a tune up the guy was like o no, 3.4 are very hard to work its gonna be alot more im like well forget the tune up and just change my plugs he said ok its gonna be 109$ just to change the plugs im like wow. so does what i said sound like it could be the spark plugs? i just drove it around it pretty much doing the same thing. taking off its screaming not really moving then bang it takes off. any help would be great i need to try and have this fixed by WED. cause i have a long trip to court and i have the climb the cajon pass which is about 5000 feet. gonna suck drinvg up the pass in the truck lane eh. thanks guys.

[Mike Jung]

Get it fixed !

If you keep driving it like this, with mis-fires; you will very soon need a new Cat (if you don't need one already).

Misfiring engines kill Cats !
(& aren't the best thing for your engine !)

[TwIsTa]

But would the misfireing just be cause of my plugs? Ya im pretty sure my cat is already out cause it rattles when i start my car when its cold and my gas milage is horrible. and is 109$ a good price to get your plugs changed or are they easy to do yourself? thank you.

[botlfed]

it is probably the cat that is plugged or the core has broken loose.

as far as the plugs, they cost about $2.00 each and takes less than a half hour to change all 6 of them

[eaglesrealm]

But would the misfireing just be cause of my plugs? Ya im pretty sure my cat is already out cause it rattles when i start my car when its cold and my gas milage is horrible. and is 109$ a good price to get your plugs changed or are they easy to do yourself? thank you.

As someone else said, the plugs are relatively cheap. I have been using the Bosch 2's for awhile now with no problems. I would not waste the money on the Bosch 4's and actually heard somewhere that they are not really good for our engines. You could use many other brands as well, I am sure.

As for the work, the front 3 take maybe 10 minutes. The backs take a bit longer, depending on how good you are and what tools you have. It's just a matter of space back there and getting your tools and hands down there.

Two things though, getting the plug wires off can be a pain in the a$$ if they are fused from many years of use. I had a couple that pulled themself apart, so that was the final straw to replace the wires at the same time.

And, most important, make sure you use a light layer of a anti-seize type grease for spark plugs. Otherwise, this could be your LAST easy plug change :)

[cc_bruno]

As botlfed said, it's more than likely a piece of your core has broken off and is restricting exhaust flow. Had that happen to my '94... couldn't get above 20 km/h with it floored. Good luck with it.