Stalling while driving

[blackheart2358]

Ok so I have a new problem and this site has always been good in the past so I'm here for info and hints once again.

The car is a 91 Chevy Camaro RS , 3.1 V6 and a 5 speed. Mileage is approx 400K + , the odometer has never worked since purchase and showed 239K when I purchased it approx 8 years ago.

The battery croaked due to being low on water and at the same time a stalling problem began so I can't help but to wonder if the battery going bad may have contributed to the stalling issue.
The battery has been replaced with a new one but the stalling issue has not been resolved by replacing the battery.

At start up the car will idle correctly, occasionally when starting the rpm's will shoot up then slowly slow to correct idle speed and usually continue to run.
When driving car seems fine but when the clutch is pushed in when coming to a stop at a sign, light, etc the engine rpm's begin to slow from traveling r's down to what would be normal idle speed, this is when it stalls.
If I left foot the brake and keep r's up with my right foot I can prevent the car from stalling. If I (using my foot on the gas) allow the r's to slowly come down to sitting idle speed it usually will not stall.

The cat converter was removed from the car several years back so it's not a clogged exhaust problem.

Any advice, hints or help is much appreciated.

[MagicRat]

My first guess is a leaking EGR valve. At idle, the strong intake manifold vacuum is able to suck exhaust gases in, reducing the amount of oxygen in the intake manifold, causing low idle and rough running. Essentially the mixture becomes too rich, the plugs load up and the engine stalls.

I should add this is a good guess, and someone might come up with a better suggestion.
The only other alternative is a dirty or blocked idle air control valve.

I suggest remove the throttle body, and use carb cleaner to clean up the IAC and see if that helps. If not, consider a new EGR.

[blackheart2358]

Thanks Magic , sounds like something to look into.

A friend with a Chevy approx the same year told me after replacing a battery it took his computer a few days to get back to normal.
While I've not had this experience in the past he assured me it happened for him that way, just wondering if any others have had this experience?

[Ironic]

You can check your fuel pressure regulator, pull the vacuum line off at the regulator and try wiping inside the nipple with a q-tip. If you smell gas- replace it. I'd check for vaccum leaks also, as that is what the syptoms suggest. Plug the brake booster vaccum line and see if that makes a difference.