My 1978 Starfire with the Chevy 305 (from the factory), 2 bbl 2GC carb, and 4-speed manual transmission. Electronic ignition from the factory. The car is as it was from the factory.

When the car is cold everything is fine. When it warms up, and I come to a hard stop, it dies (yes I have the clutch pedal depressed or am in neutral). Starts up again immediately. I unplugged the brake booster and capped the line from the carb. No difference, so it doesn't seem to be related to the brake booster vacuum. If I slow down very slowly and come to a gentle stop, it stays at idle no problem. I replaced all of the vacuum lines last fall, there are none missing. I replaced the EGR valve last fall also. I have been noticing a rough idle when warm lately.

Any ideas on where to start with this?

 

What is your idle speed?. Could be the engine needs a tune up, possibly you have a vacuum leak somewhere.
A proper tune up should reveal any underlying problems, if you need new intake gaskets or whatever you would need a tune up after the repair work anyway.

Roger.

 

What are your tune up settings?

 

There could be crud in the carb? It moves around when your stoppin hard.

 

Professionally rebuilt carb. Tuned up last fall to all factory specs. Low idle speed is 600, per spec. All new vacuum lines. I will test for vacuum leak with carb cleaner later today. If that is negative I guess I'll run through the tune up again.

 

OK, checked for vacuum leaks and found none. Checked tune-up and everything is as it should be. 4* @ 600 rpm with distributor vacuum line plugged and trans in neutral. Low idle set to 600 rpm with EGR vacuum and purge lines plugged.

Took it out for a test drive tonight, took the same route last night and could not get it to die when I braked hard. Hmmmm. Idle still seems rough though.

 

Are the a/f mixture plugs still in the carb? Have you hooked a vacuum gauge to it?

I noticed that the later year 305's the timing is set to 6 and the idle was bumped to 700.