W210 606 shut off...advice

[BiodieselMB]

Hello. Recently I changed out the shut off valve, on the 1996 W210 606, due to fuel leaking from the inside of the part not the o-ring to the injection pump. Since then the car is slow to shut down after the key is turned off. Prior to the swap the car would shut off immediately and now it varies from 1 to 3 seconds lag and sometimes accelerates prior to shut down.
What is causing this to occur?

[KarTek]

My car has done this in the past and I remember it's something simple but I can't remember what it is.

I would 1. check to make sure the o ring is installed correctly - off the shoulder and 2. make sure the electrical connector is secure and oriented properly.