I dont know what this could be but I have an 85 z28 with a 305 only has about 88,000 miles on it the carb ws changed from an electric choke to a manual both were quadrajets thats the only thing that I have dont to this car it also diesels for a few seconds before shut off but not all the time I was thinking maybe the timing or the computer any help would be appreciated

 

Did this start happening after the carb was changed? Do you have the TPS and the Air/ fuel solenoid still in the new carb? Did you kink the fuel line?

 

I dont know anything about the tps or solinoid, but I did kink the fuel line a bit trying to get the line of the other carb so I just cut it and got some rubber fuel line and fixed it that way. But whats wierd is that at idle I can rev the car until i burry the tach if I wanted. It revs with ease it does have a little shake at idle. Yes it did start after the carb was changed I think i might just go get the old one rebuilt