I have a 1984 240 Turbo. When I back off the gas (transmission in neutral), the engine RPM drops down to 500 RPM or lower, then quickly steadies out at 900 RPM. This is not a major problem except that on occasion the engine speed will drop low enough that the engine dies. The problem started happening pretty suddenly as far as I could tell. It wasn't there one day, then it was there the next day... leading me to think it's something electrical or a sensor. I've replaced some of my vacuum hoses but not all. My engine wiring harness is in pretty bad condition. My oxygen sensor was replaced last year along with fuel injector seals. I've got new plugs, wires, cap, and coil. Any suggestions would be appreciated. Thanks. ernie

Another piece of information I noticed. The car starts fine when cold. But as it warms up, it appears to have a little miss. I didn't notice the miss after I started driving the car - in fact, aside from the engine RPM "depression", the car idles pretty good when warm.