Volvo 740 Idle and Stalling Issues

[93Regina]

Was wondering if this wiring was supposed to be some kind of ground.

Haven't read all thread comments, but yes, there may be two ground straps...that connect to engine. At battery, there should be a negative terminal going to frame and engine (aka two).

Weak ground points...Shit Happens!

[Nineforty]

This is a very late reply - but did you check the seal between the bonnet and firewall? If it is clogged with gunk and dirt, the distributor cap can get wet in the rain or in a carwash, causing what feels like a bad idle from a hose leak. On my first 940 i just blew the dirt out w an air gun, and it fixed it.. but recently I had carbon buildup on one (1988 740) so bad i had to soak it in hot water soap and baking soda, and then scrape it off with a spoon! Yuck. And getting them back on the clips was almost impossible.. so i mickey mouse’d some zip ties into the clip holes and cut a tiny slit thru the seal. Did the trick.. no more leaky hood, and no more rough idles in the rain.. also - rub an ancient seal down with silicone grease before reinstalling and it will seal better and be more waterproof. Hope that helped!!