Lumpy Idle
 

I have an 85 928s with about 110,000 miles on it. The plugs and belts were changed around 60,000.

Lately the idle has been very lumpy, but when the car comes up off idle, it runs great.

Any idea what I need to improve idle?

Plugs, fuel filter,......adjustments?


thanks
bill in ca

Certainly check all ignition/tune up components and maybe replace if you've no history of their age.
Same with the fuel filter; if uknown age, replace it.
I believe the '85s had the idle stabiliser valve, these get gummed up and usually cleaned by spraying WD-40 or carb clean thru. DOn't know where exactly that's located though.
Vacuum hoses too, check everything and replace anything that look aged in any way.