The engine in my '79 Dodge Omni no longer idles when I stop at a stop sign, stop light or am going at traffic jam speeds - it just dies. As long as my foot is on the accelerator & I’m moving, I don’t seem to have any trouble - only when I need to stop. This has made driving extremely frustrating, as I’m constantly turning off the car & restarting it during routine driving. Any suggestions as to what might be going on?
When I saw “Omni” I figured this must be an old car, haven’t heard of an Omni in years. This maybe the last one running! I assume it has a carburator, and it likely in need of some carb work. The needles valve could be clogged, floats stuck, etc. It is either not getting any gas through the idling jets, or too much. If you get black smoke from the tailpipe on restarting it is too much gas.
If it is a throttle body fuel injection system something is amiss with it.
Besides the previous poster’s suggestions, check the vacuum lines in and around the carburetor for leaks or if any are disconnected.
You might also want to see if the inake manifold gasket is leaking.
Carburetors did seem to be troublesome on these cars. A friend of mine junked an otherwise serviceable Plymouth Horizon (same car) because it needed a carbuetor to run right (it was doing exactly what your Omni is doing) and a replacement carburetor cost more than the car was worth.
In addition to Triedaq’s suggestion to check for a leaking intake manifold gasket, I would also look carefully at the gasket beneath the carburetor.
IIRC, those engines used a thick semi-hard rubber gasket underneath the carburetor (perhaps for heat isolation). I remember a few of them breaking down, causing air to be sucked in.