My 1987 Z28 often drops in RPMs and begins to stall when I'm stopped for more than 10-15 seconds at a stop sign or stop light. The only way I've found for it to stay running is to put it in neutral upon stopping and lightly hold the gas down until it's my time to go. The problem only occurs when the car is in drive or reverse. I have no idea where to begin so any and all help would be appreciated.

 

Check your fuel pressure, and also your injectors. I had the same problem and it was my injectors.

 

I had the same problem when i first bought my 91, turned out to be the fuel pump going out.