What are other causes of a poor idle?

[Maggiolone]

84 Jetta 1.7

I've replaced: Injectors, seals, CO2 sensor, CO2 relay, cold-start valve, fuel accumulator, and have adjusted the timing. I've also replaced spark plugs, wires, cap and rotor.

The car *should* be fine, and yet I get a shaky, fluctuating idle.

I'm trying to figure out what else could it be. WUR? Fuel pump relay? Auxiliary air valve?

I always thought the WUR doesn't have much to do with performance beyond cold starts.

[targa]

Check for vacuum leaks. They will drive you nuts

Tom

[Maggiolone]

I've been spraying for vacuum leaks everywhere...the ONLY place I might have one is a cracked plastic fuel injector sleeve. Everywhere else seems tight

I cleaned out the WUR, and the idle doesn't seem to fluctuate when cold anymore. I'm really pulling my hair out.

[fiftybuckbunny]

Gotta get a fuel psi gauge. It's the only way to know what's going on. I also have idle and hot start issues. My new gauge arrives tomorrow! There are a couple places to get them online. About $100. Also, smoke machine is best to find vacuum leaks. Lots of shops have them now. I found my throttle body was leaking and a bunch of other little places, too. Much more accurate than carb cleaner.