M119 Oscillating Idle
 

Greetings all,

I replaced the FI wiring harness in my '95 E420 (89K miles, new distributor, wires, and plugs), and the running issues went away but for one: Intermittently when at idle in gear when hot, the idle will start to hunt between 500-800 or so, requiring me to put it in neutral to make it stop. It seems to happen more after prolonged steady speed running; around town in stop and go, not so much. It drives seemingly fine otherwise.

It also has a little off idle grumbling when driving off when restarting after the car has cooled down a bit after being hot, which goes away once the car is hot again.

I'll try cleaning the MAF and throttle actuator this weekend. Are there any obvious vacuum hoses I should look at?

Thanks,

Kristian

Typically, these types of idle problems are caused by vacuum leaks. Also, check the EGR pipes for soot blockage.