Engine Stall on incline

Hi,
I have a 96 W210 E230. It is a 4-cylinder 2.3 German Version.
There are times when the car is parked on an incline, the car does not start. The battery and starter turns fine but it doesn't start. What I do is that I lock the car, leave the car and wait for a few minutes then the car will start normally.
There are also times the idling becomes too low and suddenly dies. But at least it starts again.
I just changed the fuel filter. What are the probable cause?
Fuel pump? Relay? wiring harnesses? Dirty fuel tank? Fault in the immobilizer?

Thanks for any info.

[ssanmor]

My 190E 2.3 8valve does the same, perhaps the same problem. Unfortunately, I don't know what is the problem, I also blamed the fuel filter but if you have changed it and doesn't cure... perhaps the fuel pump. Does it make more noise than normal (can you hear it from the inside with the car in neutral? Mine does)

Any help is appreciated

[txstinger]

It could be from running a little lean or large spark plug gap.
We had a side road with a long mild incline and would test vacuum while driving with a constant throttle. Then we would pull the plugs and inspect.
http://www.centuryperformance.com/spark2.asp
A good page on plugs!

[joel]

could be something in the tank.