1988 IROC runs great with 350 (now 383).
But ... suddenly it will start to kill everytime
I come to a stop sign. I have to hold in clutch
and rev the engine - or it will kill.
This may keep up for a few hours or a day.
Then... suddenly... fine again.
Happens intermitently, but about every week or so
on average.
I put in a new fuel filter...No change.
Your opinion?

 

I would check the fuel pump or just remove the line under the hood and hook up a fuel pressure gauge to see if it is the correct fuel pressure

 

What else was done to the car? You say it stalls wehn you push in the clutch, did this car have an automatic before? (I ask because you say it used to have a 350).

 

Good question about the automatic.
No, it is a manual that had a 305.
Put a 350 (stroked to 383).
It doesn't stall when I push in the clutch, but I have to push
in the clutch and rev the engine to keep it from killing.

 

When was the last time it got an ignition tune-up/wires plugs? If its been a while, that's a cheap and fast way to rule out that type of symptom.

 

is it still fuel injected or was it converted to carb?

Do you know what was re-used vs new when the engine was rebuilt?

If not, is there a way to find out what was done to the engine and what pieces/parts were recylced and that includes sensors, wires, carb (if it's now carb) injectors etc

 

if it is still TPI, does it throw any codes? When was the last time that you cleaned out your IAC and did the minimum air adjustment?

 

I had a similar problem on a 1988 305 5 speed. It would stall everytime I applied the brakes moderately hard. Would start right back up every time.

The problem turned out to be rust inside the distributor. Both the reluctor and the teeth on the distributor exciter ring were rusted to the point where they would still make a good enough signal for the pickup coil under most conditions, but the slight G force of braking would move things around just enough that it would stall.