NewEdgeStang00

Just recently I've noticed a very rough idle on my 00 v6 auto. at parked idle it shudders a lot and you can visibly see the steering wheel shake. this also happens when accelerating under 1.5k revs, but right when I start accelerating above 1.5k then everything is smoothe.

at first it felt like the engine was unbalanced but when I checked the engine at idle it wasn't shaking at all. so I'm thinking maybe clogged up cats that need to be replaced? it is a 2000 with 190k miles and the cats appear to be stock.

also I have a dual exhaust catback and Cai so would that be affecting it in these freezing temps? sound-wise everything seems great, just the parked idle and low acceleration shudders and vibrates the steering wheel.
I will try to provide any info that I can, I noticed some other owners have somewhat similar problems.

RyansQuick6

DPFE, or IAC, possibly spark plugs/wires. If it were cats, then the engine would constantly struggle, no matter what rpm it's at.

NewEdgeStang00

Thanks Ryan. It's had new spark plugs and coil pack. Could you give some insight on DPFE or IAC?

RyansQuick6

When were the plugs and wires done, and what was used?

NeoTokyo

Possible that one sparkplug was cracked when installing too.
In a very dark area with the engine running look around the plugs, plug wires and coil pack to see if you can see any spark leaking.

Also like Ryan said, check that IAC, its the thing that sits right by the TB that looks like a bullet.

Also you could have a vacuum leak or your EGR valve is sticking open causing a leak.

There are have been a lot of people with idle issues posting all of a sudden.

RyansQuick6

The cold weather tends to freeze any moisture that may be in sensors and the expansion can cause them to stick or fail

NewEdgeStang00

They were done in July, NGK Platinum Spark plugs, OEM coil pack. Thanks for the input! I'm still new to working my way around the engine bay but I'm always trying to learn more. With the cold weather and snow out it's harder for me to spend the same time I used to outside looking in the engine bay but I will take a look and see what I can find with what you guys have mentioned. I appreciate all the input! I will try to include pics when I can if I see anything unusual.

And yes Neotokyo I've noticed a lot of the idle issues too so I'm glad to know I'm not alone. Hopefully whatever I find out with whats happening with mine can help the others too. I have had checked the EGR valve before since it did have issues with coming loose but after tightening once it's never come loose again. I had an emissions leak before but it was in front of the cats with a hole in a weld but that was a quick fix. So far EGR-wise everything seems sound.
Merry Christmas Eve!

NewEdgeStang00

UPDATE:
Something new has sprung up which may help pointing out where the direct problem is. I noticed that when I turn the heater on all shuddering immediately stops, so I'm thinking maybe a there's a pulley that kicked in and did something to smooth the engine out? Then when I turn the heater off and I'm accelerating from a stop the shuddering is back, it feels like there's a strain from underneath the car.

I've also been meaning to ask power-wise about how your guy's sixxers accelerate. Right at 1.5k it's just a very slow and steady acceleration right? Just with a little gas being fed, little light on the pedal.

99'PEGASV6

IIRC platinum plugs aren't really good for our cars or so i've heard

RyansQuick6

Get rid of those plugs and get some ngk tr5's