I have a 2003 Taurus with 48k miles and Vulcan engine. I ve had it for three months…. Cam synchro, fuel pump, spark plugs/ wires, coil pack, and trans fluid has all been done since. Car still has a rough idle at times when sitting at a light or even when in park. Sometimes it feels smooth, sometimes like the whole car is shaking, and sometimes somewhere in between those. It drives smooth. I suspect vacuum leak, but any other ideas? No engine light either. Also for vacuum leak do I just use carb spray or listen for difference? Any tips, thoughts, or advice would be appreciated, thanks.
You might try cleaning the MAF sensor and throttle body. Vacuum leaks are pretty likely on vehicles whose age is measured in decades. You can listen for leaks or use something like carb cleaner to look for them, or a smoke test. Uneven compression can also cause a rough idle as can leaky fuel injectors.
It would also be a good idea to scan for codes and live data to get an idea of what's going on.
