99 wrangler high idle rmp and hissing noise

So as I was parking my car and I accidentally stalled it. So anyway I return to the car 20 minutes later to leave and when I start it up I notice the engine is idling at 2000 rpm and is making a loud hissing noise from the drivers side on the engine (I think). When I revv the engine it is slow to come back down to the 2000 rpm idle. When I put the car in gear and drive it, it likes to stay at 2000 rpm. The car will accelerate without me pushing the gas pedal until it reaches 2000 rpm. Also when I shut the engine off, it sputters and coughs, almost like a backfiring motorcycle but rhythmically slowing down until it finally stops (around 3 seconds or so from when I turn the key off). I have looked online and I can’t find any information on it… Please help… The check engine light is OFF and the car is still “drivable” (I got it home) and typically idles around 900 rpm I think.

you have a vacuum leak somewhere.
open the hood and try to track the sucking noise down.

Especially check the hose from the power steering booster.


I agree with Yosemite (as I frequently do) that you have a vacuum leak, but I believe that he misspoke when he stated “power steering booster”. Clearly, he meant to say that you should check for a disconnected vacuum hose leading to the power brake booster.

Nice catch @VDCdriver!!! I could’a gotten hurt from a fall like that.


Thanks a lot for you’re answers! Is this something I could fix or am I best taking it to a shop? I’m not a mechanic by any means…

Now that you mention the brakes, the brake light stays on dimly (gets brighter when the emergency brake is on) it never has done that before…

Also is it safe to drive to a shop?

There may be more than one issue.
More than likely, that brake warning light serves a dual purpose–to remind you that the e-brake is on, and also to tell you that the brake hydraulic fluid is low.

Open up the master cylinder and check to see if the level of the fluid has dropped to a significant extent. If it has, have somebody drive you to the nearest auto parts store to buy a bottle of the correct specification brake fluid.

Add fluid up to the full mark (or close to it), and then drive it to a trusted mechanic’s shop in order to have him check the condition of your brake pads. Usually when the brake fluid level falls, it is an indicator that your brake pads have a lot of wear on them.

While the car is in the shop, report the other symptoms and have him check for a disconnected vacuum hose or other cause of the idling problems. A gunked-up Idle Air Control valve is another possible cause for the high idle speed.

The gunked up idle air control valve is what a local mechanic suggested when I described the problem to him. Thanks again for all you’re help. I really appreciate it.

While a gunked up IAC could certainly cause that it doesn’t explain the hiss. I agree with the others that a bad vacuum leak is more likely the cause for the high idle.

Chech around the brake master cylinder and the large, round booster behind it. You should find the vacuum hose that goes to the booster. Just push it back onto the nipple that it came off of. No tools should be needed.

I had one do this to me once.
While you are in that area check the fluid level too.


yep, sometimes that hose will crack where it goes on the nipple too. when you stalled the jerking motion may have cracked or dislodged the hose in question.

wow I used a lot of words that could be taken out of context there…

It could also be a bad grommet for the brake booster hose connection. The truck is 15 yo. Any number of things could be causing the leak, but I’d check anything made of rubber or plastic.