i have a '78 240d that just recently started to run at high rpm's, when i start it its ok, but after it gets warmed up the rpm's just shoot up..

even when its on neutral its running high, after a while its slightly goes down but not much and it just stays there.

any help will be appreciated
thanks...

 

My guess would be a sticky throttle linkage, maybe kube it up a bit.

 

yeah im familiar with that ****, its been down, never quite moved it before.
The thing is the rpms go up with higher temp. when i start it its ok

 

I'm having a similar but not exactly the same problem, My 240 is idling a little erratically but it doesn't slowly increase rpms. Maybe lubricate your entire throttle linkage, Try Disconnecting the small vacuum line connected to the back of the fuel pump. If your car has a kick-down plate (my 300d has one) check it, Its behind the gas pedal and if it looks like a button stuck in the down/push position try pulling it back out.

Just some ideas.

 

I recently started experiencing the same symptoms on my 1961 190Db. If you solved your problem, I'm very interested in what you discovered. Obviously the problem is too much fuel, but where the problem is...??? I think my first step will be to pull the injectors and try to rebuild them.