Real Idle problems

Hello! I'm new here on the forum and look forward to hearing what some of you have to say. I have a 94 3000GT that I love, so it goes to the shop with any little problem to be fixed right away, and I have followed all the recommended mx. I actually just picked it up a few days ago after having the oil changed and new door locks installed (that wasn't cheap btw). The next day though, it started acting up when I tried to start it up to leave work. It would try to start, but the engine would chug and then it would die. Once I would get it started and keep the gas pedal down a bit, it would stay running (I don't live in a cold place if that's what you are thinking). Once I would let off the gas, it would die. This would occur intermittently because later that day, it started fine and ran fine for awhile. Sometimes, I could get it running and when I'd start to slow down or come to a stop the whole car would just shutdown at around 1000RPM (that's a bit scary in a turn). But, again, as long as I kept the gas pedal down and kept the RPM up, it would be fine. I took it to the shop the first time, and they couldn't get it to repeat this behavior. I then drove it for about a day before the problem came back. I have no check engine light with this, the fuel filter/pump is fine, and the plugs/wires were just replaced last summer. The shop now tells me that it could take up to $1100 to replace a throttle body complex, or they could maybe rebuild a dashpot(sp?) part that may last or it may not. Has anyone experienced anything like this or have any puts before I let the shop start troubleshooting this problem part by part at my expense????? Help!!! Thanks!!!

Check to make sure your MAS is connected snug...if not that it could be your IAC

Does it sound like it's missing really bad when at higher RPMs... or does it run really rich... I'm gonna go with what he said ^^^... check those two things... b/c I had forgot to plug my MAS after doing some work... it'd run... but not idle... and ran very bad (lean)... and another time, after putting on my CAI, the hose clamp busted and the CAI blew off, pulling a wire out of the TPS... this made the car run really rich...
for that IAC, you can take some intake cleaner/carb cleaner and spray over it... and that may help...

I'd try these things first... then if that doesn't help, put some fuel treatment in and give it awhile... keep us updated on what you find...

another thing I just thought of... check to make sure you don't have any splits in hoses or anything... I'm assuming you have an SL... some vaccuum hoses can split over time and cause similar problems...

Thanks for the puts so far. I will check out the things you all mentioned. The shop did mention that it could be the IAC as well, but again, they just seem unsure. If anyone thinks of anything, let me know... I'll keep you updated on what I find.

And you're correct...it's an SL.

Don't pay anybody a grand to do anything. I would seriously think it is something to do with your intake system. Either a faulty/loose sensor, such as the MAS plug, or the IAC.

Or it is a loose/disconnected intake pipe or vaccuum hose.

Just start checking every pipe and hose connection. You could also try disconnecting your intake pipe from the throttle body and check to make sure that the butterfly valve is working correctly inside.

Check your battery gauge. A while back, my car would start up but would then shut down because it wasn't getting any power at all. It turned out that I just needed a new alternator. This probably isn't the solution, but it's worth a try I guess.

The way your describing it, it sounds like the same thing that happened to me, it turned out to be my Underdrive Crank Pulley the guy said. Every time ya slow down or stop ya have to try and brake and hold the clutch in and give it gas all at the same time so it wont die. lol. what a pain in the ass! But then agian maybe its one of the things the other guys are talking about.......good luck man

So here's the deal. I took the car to a different shop to have them check out the car and consider the inputs you all have given me so far. They had it for 4 days and the car didn't act up once, so they wanted me to pick it up. Well today, it acted up, but with different symptoms than before. This time, as opposed to wanting to die/shutdown as I started slowing down, the RPM would pulse around 1500-2500RPM. I would even be stopped and have it in neutral and the engine would be surging (with the RPM bumping around). Then, when you'd be cruising, you could take your foot off of the gas pedal and the car would run like it was on cruise control -- almost like it had a mind of its own and was driving itself. It wouldn't be smooth though, the RPM would jerk around a little. I felt like I had to cram the brakes to get the car to stop though. It was like the RPM couldn't go below 1500. So, what could be causing these two totally different problems to occur?? And sporatically???? I think the MAS is fine and all the hoses are good. IAC? ECU? Aghhh.

Again man, check all your hoses and intake pipes, a large vacuum leak could be the cause, and if you've never pressure tested, then chances are you have plenty of leaks. Just because you can't necessarily see them, doesn';t mean they aren't leaking large quantities of air.
Also again, your IAC is a great place to start, as it causes very similiar symptoms to the ones you are describing.
Just turn the car on, get under your hood and listen for leaks. Rev teh car up and down a few times to try and simulate it.

The way your describing it, it sounds like the same thing that happened to me, it turned out to be my Underdrive Crank Pulley the guy said. Every time ya slow down or stop ya have to try and brake and hold the clutch in and give it gas all at the same time so it wont die. lol. what a pain in the ass! But then agian maybe its one of the things the other guys are talking about.......good luck man

Increase the idle screw on the butterfly (throttle body)... this will keep you from having to always give it gas... it will take some experimentation and maybe an hour, but I think it'd be worth it...

Well, after a long tedious process, it seems the 3000GT may be fixed. The shop found that they needed to replace the fast idle air control valve, a cooler hose, and the IAC. And it seems to be running great for the moment...thanks for all your help!

GTBlues,
I read your post as I am experiencing the same problems with my 94 3000GT. Can you please tell me if replacing the IAC (is that the Idle Air Control?) and the fast idle air control valve and cooler hose fix your problem? would you also be able to tell me how much it cost overall? PLEASE HELP!! Any assistance would be greatly appreciated.

SSGT Garcia

Holy old thread!

SSGT, please start a new thread, describing your exact problems. Most likely it is the IAC, that needs to be cleaned or replaced.

http://www.stealth316.com/2-isc-iac.htm

you can find a used one on ebay usually for around $50