Rough Idle and Occasional Stalling on My 964 – Need Advice

[Trentonvale]

Hi everyone,

I’ve been having an issue with my 964 lately and wanted to see if anyone here has experienced something similar. The car runs fine when cruising, but when idling it sometimes feels rough and, on a few occasions, it has even stalled when coming to a stop.

Here’s what I’ve noticed so far:
• Idle is inconsistent, hovering around 700–900 RPM
• Occasional fuel smell when sitting in traffic
• Stalls randomly after longer drives
• Car starts back up without too much trouble

What I’ve checked/done:
• Spark plugs are fairly new
• Air filter is clean
• No visible vacuum hose cracks (at least at first glance)
• ICV looks a little dirty, but I haven’t cleaned it yet

Could this be an idle control valve issue, vacuum leak, or something DME related? Before I start throwing parts at it, I’d love to hear some thoughts from the community.

Thanks in advance for any guidance 🙏

[Kevin Stewart]

Do a search on the 911 page on 3.6 conversions.

[chucksmith]

cleaning the ICV is easy and a good place to start, check for vacuum leaks while in the area.

[TorqueHead]

Do you drive it much? Just asking because the fuel might be stale and that won't help it idle properly.

Any mods or recent work on it?