Just started today with weather of 5* and wind factor of -15* . So car has been running very good , 1989 740GL with 431K milage. Cold start is no problem but instead of settling down to 700 rpm idle it stays at 1500 rpm. Also started to hunt from 1500 to 1000 to 1500 , etc. Drives fine with no missfires or stalling. Idles in drive at 1000 rpm. Shut it down and turns off but rich gas smell. I'm thinking cold start valve or sensor. To cold to play with it now but and suggestions would be appreciated. Thanks

 

Any codes? How is your IAC? I know in cold weather (around zero F) a dirty IAC will stick. Usually will clear once the engine is warmed up though. Other standard culprits are air leaks in the intake between the AMM and the throttle body. But you know all this.

 

Well it's fixed or maybe not. Finally had a weather break and temps are in the 20's now. So got into the car a day after the idle problem happened and low a behold it is back to normal. Also put gas in it today and only got 18 mpg. which either could be from the week or two of minus zero weather or the idle problem. So I'll continue to drive it and see if the issue comes back . As the weather warms up I'll do all of the normal TB and IAC cleaning. Just wanted to get back here. I don't like magic fixes so we'll just have to see.