Hi all. Just bought a 2001 GP GT. Fixing it up and after removing 3 broken plugs in rear thought I could get over the hump but not yet. Car is rough idling until I plug up a stubby hose same line asr brake booster hose? When I stick a pencil in the top of it (It sucks air in) engine idles much smoother. Do you know what this line is and where it should be attached if anywhere?:



THANKS I am fixing this car for my son. He loves the look of this car and I do too!

Welcome to the forum Joe.
The video is not loading, can anyone else see it?..
Even some photos of the vacuum line would be helpful.

Can't see it. Asks me to sign in before I can view it.

THanks guys how is this jeesh I sound like Danger Will Robinson Danger!:

Usually only 2 hoses come off that fitting on the backside. One goes to your brake booster(large hose) and the other goes to your HVAC controller. Unless you have electronic climate control that does not use vacuum, then stick a bolt in it and be done with it. But I'm going to assume that there is a vacuum hose laying back there somewhere.

With my 3800 II that vacuum hose goes to the HVAC controller as Mike mentioned, but it also Tee'* off from the large wire loom that runs it to the HVAC, and it runs around the body of the passenger side of the car, until it gets to the front area, then it goes down near the front bumper, then across the bumper till it gets to the EVAP Vapor Canister, which on my car is located under the air-box and PCM.
When you let it run for a bit while plugged does it throw any DTC'*?
I'd have it scanned for trouble codes if you have not already done so.
I don't have the diagrams for the EVAP routing on hand, or I'd post them, maybe somebody else will be able to provide them.

Thanks Mike and WilliamE. William the check engine lite has been on since I bought it. Because it is grandfathered with emissions in a few months I figured if there is too much of latter work $$ to do indeed a bolt in the vacuum line is fine with me and I will wait till Jan. 1 to get a sticker for my son to use it as his. The car only has 100k but rocker panels are gone (major problem with this car and the plastic lining) so I guess I will fix those up to get a sticker. Thank goodness for the easyout to get the broken plugs out of head in rear. Tranny was a little rough shifting with a small clunk into Reverse but yesterday I dropped the Pan replaced the tranny filter and put in 8 quarts of Royal Purple. After a few trips up and down the street it is shifting easier now and is a bit quieter. Tomorrow it goes into the shop as the steering rack is likely gone and I will have him check the car codes DCTs ?... Thanks again.... Joe

Here'* the vac lines. The evap cannister looks like it'* back at the fuel tank.

Thanks Mike and WilliamE. William the check engine lite has been on since I bought it. Because it is grandfathered with emissions in a few months I figured if there is too much of latter work $$ to do indeed a bolt in the vacuum line is fine with me and I will wait till Jan. 1 to get a sticker for my son to use it as his. The car only has 100k but rocker panels are gone (major problem with this car and the plastic lining) so I guess I will fix those up to get a sticker. Thank goodness for the easyout to get the broken plugs out of head in rear. Tranny was a little rough shifting with a small clunk into Reverse but yesterday I dropped the Pan replaced the tranny filter and put in 8 quarts of Royal Purple. After a few trips up and down the street it is shifting easier now and is a bit quieter. Tomorrow it goes into the shop as the steering rack is likely gone and I will have him check the car codes DCTs ?... This car was sold as a RUNS and Drives aka ready for the scrapheap. I though I could resurrect it if I got it cheap. I picked it up on craigslist for around 1K and have $200 into it. Sofar so good. You wouldn't believe (sure you would) the shitbox Mustangs I looked at cuz my son only wanted that car. They were so beat up by young kids and cost 4X the cost of this Grand Prix. AFter he saw this he said Dad I actually do like it! Dual exhaust peppy with torque, what'* not to like at this price. Plenty of room in the back for his friends too unlike the Mustang. I don't know who'* more excited him or me! Thanks again fellas

Thank you soft ride! Great to be here. Very helpful community...