I have an 84 Camaro with the 305 and a the original quadrajet carb. A while back i had a problem with the car "dieseling" out when i turned it off. While looking at the motor i found that the idle stop solenoid was completely fried and corroded so i replaced it. This fixed my original problem but now i have had a new one come up since. The car runs fine up until about 40-mph, as long as i stay below it i have no problem but if i go over 40-mph the throttle seems to stick like some automatic cruse control, and will continue to stay like this untill i slow down to about 35-mph then it seems to just shut off. To fix this problem i can pull out the choke fuse, my light comes on, on the dash, but the car runs perfect until i go to park it and the idle is high and it "diesels" out... This has been racking my brain and ive run out of ideas. It has to be something to do with the choke, i just cant figure it out. Maybe someone else has had this problem and can help, i could use it.

 

Check to see if the choke is fully open (90 degrees straight up) when it does this. It should be open when fully warm and allow the fast idle cam to drop. When you pull the fuse the choke will not open and the fast idle cam keeps the idle speed bumped up.

Your sticking throttle could be caused by weak throttle return springs (there should be two, one inside the other) or a sticking throttle shaft. Take all of the assorted cables off of the shaft and check for play and binding. The throttle shaft bore can wear (wallow out) and the throttle will stick. Check it for play with it partially open so the throttle blades don't keep it locked in place.

If the shaft bore in the bottom throttle body is worn it can be bushed with a kit.

 

I checked the linkage and choke out and it didnt seem to be getting caught up anywhere and the choke opens up when the motor is warm like it should. I only have this problem when im driving down the road at 40+. I would think it to be something in the transmission because i can put it in park and rev it up with no problem, its just while im driving that it has this problem. But if so i dont see how pulling the choke fuse would have any affect on the transmission.

 

Check the throttle idle speed compensator. It's the solenoid that bumps up the idle speed under certain ECM or AC commanded conditions. Disconnect it and see if anything changes.