I've noticed recently that when I am at a traffic light with the car in drive (automatic) and completely stopped the car has a strange idle, where it will idle fine but every 2-4 seconds the engine rumbles a bit. When the car is in park the idle is completely fine. Any ideas?
289 4V w/ Automatic

Thanks...

 

Most likely your carburetor either needs to be adjusted or needs to be rebuilt. Do yourself a favor and make sure the fuel line filter is clear and that you have fresh fuel in the tank.

 

If it were the carb, wouldn't the problem also be symptomatic when in Park and idling? The carb was rebuilt back in November. The fuel should be fresh I filled up today.

 

No, because you have no load on the engine at idle. Once you add a load to the engine, you need for everything to be adjusted properly for optimum performance. Since you have fresh fuel and maybe can take the carb out of the equasion, how about the fuel pressure to the carb

 

I should add that once in a while if I give the car alot of gas and then suddenly let go, the car will stall. Only happens if at very low speeds, like at a traffic light or in stop and go.

 

Update #2, drove the car this morning and was idling perfectly for the first 15-20 minutes, until theengine warmed up and then it came back...

 

Mine just started doing the same thing yesterday (at a traffic light, it's idling so hard I'm going up and down so much I can't see straight)... Thanks Soaring for the advice, I'm going to switch out my fuel filter... adjust the carb... and hopefully that'll fix it.

Is there anything else that could be done without rebuilding the carb?

 

Don't forget your vacuum hoses. When you are in gear your engine is loaded, when in park your are unloaded and at a slightly higher idle. A small vauum leak will have a greater impact at the lower idle.

 

I'm going to have to do some research on the vacuum hoses... I just don't know anything about that part of the system.

The other day, I removed my a/c condensor, and started removing the a/c components... The compresor, filter, and the two hoses going through the firewall are stil there. Could I have messed up some of the vacuum hoses when I pulled these other items?

 

If the hoses are original they might have cracked from just being moved while you were working in the engine compartment or under the dash.